JP4260358B2 - Light guide plate and flat illumination device - Google Patents

Light guide plate and flat illumination device Download PDF

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JP4260358B2
JP4260358B2 JP2000367324A JP2000367324A JP4260358B2 JP 4260358 B2 JP4260358 B2 JP 4260358B2 JP 2000367324 A JP2000367324 A JP 2000367324A JP 2000367324 A JP2000367324 A JP 2000367324A JP 4260358 B2 JP4260358 B2 JP 4260358B2
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light
face
guide plate
light source
incident end
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JP2002169034A (en
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裕夫 庄野
司 遠藤
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日本ライツ株式会社
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【０００１】
【発明の属する技術分野】
この発明は、光源がＬＥＤ等の点光源からなり、全反射等を利用して点光源からの光線を左右方向に分散させて小型液晶表示装置等のバックライトに使用できる均一な出射光の実現を可能にする導光板および平面照明装置に関する。
【０００２】
【従来の技術】
従来の導光板および平面照明装置としては、導光板の裏面側に白インク等でドット印刷を施すとともに反射シートを設け、導光板の表面上にＬＥＤのような点光源に対応するように凸状や凹状の形状を線形や非線形にグラデーション加工を施し、光源からの光を凸状や凹状の形状部分で反射や屈折により光の拡散や集光の作用を用いて輝度の向上を図るものが知られている。
【０００３】
また、従来の平面照明装置として、導光板の表面部全体から出射する目的で、点光源を導光板の入射端面部近くに並設するとともに入射端面部の全面に対して上下方向（厚さ方向）にプリズム面を設けるものが知られている。
【０００４】
さらに、従来の平面照明装置として、例えば特開平６−５１１３０号公報に示すように、入射面側の側面に点光源を設置するための凹部を複数設け、これら凹部と凹部との間に略三角状の切れ込みを設け、点光源の両側面方向に向う光線を凹部で導光板内に取り込み、さらに導光板内の両側面方向に進んだ光線を略三角状の切れ込み部で全反射し略反入射面方向に進ませて導光板の輝度を向上させるものも知られている。
【０００５】
【発明が解決しようとする課題】
しかしながら、従来の導光板および平面照明装置では、導光板の裏面側に白インク等でドット印刷を施すとともに反射シートを設け、導光板の表面上にＬＥＤのような点光源に対応するように凸状や凹状の形状を線形や非線形にグラデーション加工を施し、光源からの光を凸状や凹状の形状部分で反射や屈折により光の拡散や集光の作用を用いて表面に出射させるように、導光板の表面側と裏面側とに対して光の制御を行っているが、側面側に対しては反射シートによって単に反射させるのみであるために、側面側の光を有効に利用していない課題がある。
【０００６】
また、従来の平面照明装置として、導光板の表面部全体から出射する目的で、点光源を導光板の入射端面部近くに並設するとともに入射端面部の全面に対して上下方向（厚さ方向）にプリズム面を設ける構成では、図９に示すように、プリズム面５１を設けた場合、プリズム面５１を設けないフラットな入射面５２で屈折した光線Ｌｆ（点線で示す）よりもプリズム面５１で屈折した光線Ｌｐ（実線で示す）の方がより両端側に光線が進み、各点光源からの広がった光線を利用しているが、点光源に於ける中心の出射光は導光板に対して入射角が３５°で５０％エネルギ強度であるので、点光源に於ける両サイドからの出射光は直進光よりもエネルギ強度が低い。
【０００７】
また、導光板に入射する光は、導光板に入射しうる入射角度に依存しており、一般に導光板に対し屈折率ｎに応じた屈折角βで入射し、光源側の入射端面部の法線と成る屈折角βは０≦｜β｜≦ｓｉｎ-1（１／ｎ）を満たす範囲で導光板内を進行する。
【０００８】
このため、点光源に於ける両サイド方向の光は、光束コーンの端部付近であり、導光板に入射する光束の厚さ方向に対応した入射角度範囲が少ないため、導光板に入射する上下方向の範囲が小さくなってしまい、全反射を引き起こす光線量が少ない。また、臨界角は、導光板と空気層（屈折率ｎ＝１）との境界面に於いて、ｓｉｎα＝（１／ｎ）により表わすことができる。そして、一般の導光板に使用されている樹脂材料であるアクリル樹脂の屈折率はｎ＝１．４９程度であるので、臨界角αはα＝４２°程度になるが、全反射を引き起こすような臨界角に近い出射角での光線量が少ないので、臨界角を破り導光板外部への出射する光線が少ない。その結果、導光板全体としての輝度低下をしてしまう課題がある。
【０００９】
さらに、従来の平面照明装置として、例えば特開平６−５１１３０号公報に示すように、入射面側の側面に点光源を設置するための凹部を複数設け、これら凹部と凹部との間に略三角状の切れ込みを設け、点光源の両側面方向に向う光線を凹部で導光板内に取り込み、さらに導光板内の両側面方向に進んだ光線を略三角状の切れ込み部で全反射し略反入射面方向に進ませて導光板の輝度を向上させる構成では、光源の左右方向に進む光線に対して略三角状の切れ込み部によって全反射を引き起こすが、上記説明と同様に点光源に於ける両サイド方向の光は、光束コーンの端部付近であるので、導光板に入射する光束の厚さ方向に対応した入射角度範囲が少ない。このため、導光板に入射する上下方向の範囲が小さくなってしまい、全反射を引き起こすような臨界角に近い出射角での光線量が少ないので、臨界角を破り導光板外部への出射する光線が少なく、光源から反射端面部方向に直接進む光線量は多い。その結果、導光板全体として輝度斑や輝度の均一性を改善できない課題がある。
【００１０】
そこで本発明は、このような課題を解決するためなされたもので、その目的は点光源に対応した位置に台形状を突設し、この台形状内に対称性を有した三角形形状や台形形状に貫欠し、光源からの光線を突設した台形状の側面側や貫欠した三角形形状や台形状の辺で全反射をし、光線を左右に広げるとともに突設した台形状の光源側を楔状のように三角柱形状に欠切して導光板に入射する時点で光源からの光線を表面部方向や裏面部方向に導くことにより、全反射の利用によるロスの低減により導光板の大きさに係り無く斑の無い明るい出射光を得ることができる導光板および平面照明装置を提供することにある。
【００１１】
【課題を解決するための手段】
前記課題を解決するため請求項１に係る導光板は、入射端面部側に台形状の凸凹構造を有し、光源側に突設する台形状の平行な対辺の短辺を入射端面部とするとともに光源側に突設する台形状内に入射端面部方向が短く、反射端面部方向が長い台形形状を貫欠することを特徴とする。
【００１２】
請求項１に係る導光板は、入射端面部側に台形状の凸凹構造を有し、光源側に突設する台形状の平行な対辺の短辺を入射端面部とするとともに光源側に突設する台形状内に入射端面部方向が短く、反射端面部方向が長い台形形状を貫欠するので、対称性を有した三角形形状で全反射した光線が反射端面部方向に直進するものと、両側面部方向に進み突設する台形状部で再び全反射をして反射端面部方向に進むものと、また光源からの直射光線とともに互いに混ざりながら反射端面部方向に進むとともに光源からの光束コーンの中心部を利用するので、上下左右方向に対し有効な光束コーンが存在し、導光板の表面部と裏面部との上下方向に対して十分な全反射を引き起こすことができる。
また、対称性を有した三角形形状で全反射した光線が反射端面部方向に直進するものと、両側面部方向に進み突設する台形状部で再び全反射をして反射端面部方向に進むものと、また光源からの直射光線とともに互いに混ざりながら反射端面部方向に進むとともに光源からの光束コーンの中心部を利用するので、上下左右方向に対し有効な光束コーンが存在し、導光板の表面部と裏面部との上下方向に対して十分な全反射を引き起こすことができるとともに光源の左右方向の光線も台形状部に放出できる。
【００１３】
また、請求項２に係る導光板は、入射端面部側に台形状の凸構造を有し、光源側に突設する台形状の平行な対辺の短辺を入射端面部とするとともに光源側に突設する台形状内に対称性を有した三角形形状を貫欠することを特徴とする。
【００１４】
請求項２に係る導光板は、入射端面部側に台形状の凸構造を有し、光源側に突設する台形状の平行な対辺の短辺を入射端面部とするとともに光源側に突設する台形状内に対称性を有した三角形形状を貫欠するので、対称性を有した三角形形状で全反射した光線が反射端面部方向に直進するものと、両側面部方向に進み突設する台形状部で再び全反射をして反射端面部方向に進むものと、また光源からの直射光線とともに互いに混ざりながら反射端面部方向に進むとともに光源からの光束コーンの中心部を利用するので、上下左右方向に対し有効な光束コーンが存在し、導光板の表面部と裏面部との上下方向に対して十分な全反射を引き起こすことができる。
また、対称性を有した三角形形状で全反射した光線が反射端面部方向に直進するものと、両側面部方向に進み突設する台形状部で再び全反射をして反射端面部方向に進むものと、また光源からの直射光線とともに互いに混ざりながら反射端面部方向に進むとともに光源からの光束コーンの中心部を利用するので、上下左右方向に対し有効な光束コーンが存在し、導光板の表面部と裏面部との上下方向に対して十分な全反射を引き起こすことができるとともに光源の左右方向の光線も台形状部に放出できる。
【００１９】
さらに、請求項３に係る導光板は、三角形形状を、対称な２つの三角形形状の３つの頂点の何れかの頂点が入射端面部の方向に向き、互いに向き合う辺が平行に位置してなることを特徴とする。
【００２０】
請求項３に係る導光板は、三角形形状を、対称な２つの三角形形状の３つの頂点の何れかの頂点が入射端面部の方向に向き、互いに向き合う辺が平行に位置してなるので、小さな突設の台形状部で対称性を有した三角形形状で全反射した光線が反射端面部方向に直進するものと、両側面部方向に進み突設する台形状部で再び全反射をして反射端面部方向に進むものと、また光源からの直射光線とともに互いに混ざりながら反射端面部方向に進むとともに光源からの光束コーンの中心部を利用するので、上下左右方向に対し有効な光束コーンが存在し、導光板の表面部と裏面部との上下方向に対して十分な全反射を引き起こすことができる。
【００２１】
また、請求項４に係る導光板は、三角形形状を、対称な２つの三角形形状の３つの頂点の何れかの頂点が入射端面部の方向に向き、三角形形状の間隔が頂点側の方が狭く位置してなることを特徴とする。
【００２２】
請求項４に係る導光板は、三角形形状を、対称な２つの三角形形状の３つの頂点の何れかの頂点が入射端面部の方向に向き、三角形形状の間隔が頂点側の方が狭く位置してなるので、対称性を有した三角形形状で全反射した光線が反射端面部方向に直進する少ない光線と、両側面部方向に進み突設する台形状部で再び全反射をして反射端面部方向に進む多くの光線と、また光源からの直射光線とともに互いに混ざりながら反射端面部方向に進むとともに光源からの光束コーンの中心部を利用するので、上下左右方向に対し有効な光束コーンが存在し、導光板の表面部と裏面部との上下方向に対して十分な全反射を引き起こすことができる。
【００２３】
さらに、請求項５に係る導光板は、三角形形状を、対称な２つの三角形形状の３つの頂点の何れかの頂点が反射端面部の方向に向き、三角形形状の間隔が頂点側の方が狭く位置してなることを特徴とする。
【００２４】
請求項５に係る導光板は、三角形形状を、対称な２つの三角形形状の３つの頂点の何れかの頂点が反射端面部の方向に向き、三角形形状の間隔が頂点側の方が狭く位置してなるので、対称性を有した三角形形状で全反射した光線が反射端面部方向に直進するものと、両側面部方向に進み突設する台形状部で再び全反射をして反射端面部方向に進むものと、また光源からの直射光線とともに互いに混ざりながら反射端面部方向に進むとともに光源からの光束コーンの中心部を利用するので、上下左右方向に対し有効な光束コーンが存在し、導光板の表面部と裏面部との上下方向に対して十分な全反射を引き起こすことができる。
【００２５】
また、請求項６に係る導光板は、突設する台形状と三角形形状とは、台形状の斜辺と、この斜辺に対向する三角形形状の辺とが常に光源からの光線を辺で全反射し、斜辺で再び全反射させて反射端面部方向へ導くことを特徴とする。
【００２６】
請求項６に係る導光板は、突設する台形状と三角形形状とで、台形状の斜辺と、この斜辺に対向する三角形形状の辺とが常に光源からの光線を辺で全反射し、斜辺で再び全反射させて反射端面部方向へ導くので、三角形形状の配置角度に依存せずに台形状の斜辺で全反射を行うことができる。
【００２７】
さらに、請求項７に係る導光板は、三角形形状のうち導光板の両側面部側に位置する三角形形状の対称位置に有る三角形形状が他の三角形形状よりも小さいことを特徴とする。
【００２８】
請求項７に係る導光板は、三角形形状のうち導光板の両側面部側に位置する三角形形状の対称位置に有る三角形形状が他の三角形形状よりも小さいので、この小さい三角形形状によって対称位置にある三角形形状からの全反射された光線の進行を阻止せずに、これらが配置されている反対側の側面部方向に光線を進行させることができる。
【００２９】
また、請求項８に係る導光板は、入射端面部側は台形状の凸凹構造を有し、光源側に突設する台形状の平行な対辺の短辺を入射端面部とするとともに光源側に突設する台形状内に入射端面部方向が短く、反射端面部方向が長い台形形状を貫欠することを特徴とする。
【００３０】
請求項８に係る導光板は、入射端面部側は台形状の凸凹構造を有し、光源側に突設する台形状の平行な対辺の短辺を入射端面部とするとともに光源側に突設する台形状内に入射端面部方向が短く、反射端面部方向が長い台形形状を貫欠するので、光源からの直進する光線を極めて少なくし、大部分の光線が両側面部方向に進み突設する台形状部で再び全反射をして反射端面部方向に進み、隣接する各台形状部での全反射光が互いに混ざりながら反射端面部方向に進むとともに光源からの光束コーンの中心部を利用するので、上下左右方向に対し有効な光束コーンが存在し、導光板の表面部と裏面部との上下方向に対して十分な全反射を引き起こすことができる。
【００３１】
さらに、請求項９に係る導光板は、中心位置に反射端面部方向を底辺とする台形形状に欠切した台形状を光源側に複数突設することを特徴とする。
【００３２】
請求項９に係る導光板は、中心位置に反射端面部方向を底辺とする台形形状に欠切した台形状を光源側に複数突設するので、光源から直進する光線を極めて少なくし、大部分の光線が両側面部方向に進み突設する台形状部で再び全反射をして反射端面部方向に進み、隣接する各台形状部での全反射光が互いに混ざりながら反射端面部方向に進むとともに光源からの光束コーンの中心部を利用するので、上下左右方向に対し有効な光束コーンが存在し、導光板の表面部と裏面部との上下方向に対して十分な全反射を引き起こすことができる。
【００３３】
また、請求項１０に係る導光板は、入射端面部に突設する台形状は、反射端面部方向に表面部と成す角度と裏面部と成す角度とが等しい台形形状に欠切することを特徴とする。
【００３４】
請求項１０に係る導光板は、入射端面部に突設する台形状は、反射端面部方向に表面部と成す角度と裏面部と成す角度とが等しい台形形状に欠切するので、導光板に入射する入射光線が最初から表面部方向と裏面部方向に進み、より多くの臨界角を破る光線量を増やすことができる。
【００３５】
さらに、請求項１１に係る導光板は、表面部に導光板内の光を出射または／および裏面部方向に屈折または／および反射させるプリズム、溝および凸凹形状のいずれかを有することを特徴とする。
【００３６】
請求項１１に係る導光板は、表面部に導光板内の光を出射または／および裏面部方向に屈折または／および反射させるプリズム、溝および凸凹形状のいずれかを有するので、導光板内の臨界角に満たない光線を屈折させて表面部から出射させたり、全反射する光線の位置をコントロールして裏面部方向に偏向させることができる。
【００３７】
また、請求項１２に係る導光板は、裏面部に導光板内の光を出射または／および表面部方向に屈折または／および反射させるプリズム、溝および凸凹形状ならびに白色系印刷のいずれかを有することを特徴とする。
【００３８】
請求項１２に係る導光板は、裏面部に導光板内の光を出射または／および表面部方向に屈折または／および反射させるプリズム、溝および凸凹形状ならびに白色系印刷のいずれかを有するので、導光板内の臨界角に満たない光線を屈折させて裏面部から出射させたり、全反射する光線の位置をコントロールして表面部方向に偏向させたり、裏面部に到達する光線を反射させることができる。
【００３９】
さらに、請求項１３に係る平面照明装置は、半導体発光素子からなる光源と、
光源からの光を導く入射端面部と、この入射端面部の反対側に位置する反射端面部と、入射端面部から導いた光を出射する表面部と、表面部の反対側に位置する裏面部と、入射端面部と表面部側とに直角に交わる側面部とを有し、三角形形状または台形形状を貫欠した複数の台形状を入射端面部側に突設した導光板と、
光源と導光板とを保持するケースとを具備し、
光源は台形状の中心位置に対向して配置することを特徴とする。
【００４０】
請求項１３に係る平面照明装置は、半導体発光素子からなる光源と、
光源からの光を導く入射端面部と、この入射端面部の反対側に位置する反射端面部と、入射端面部から導いた光を出射する表面部と、表面部の反対側に位置する裏面部と、入射端面部と表面部側とに直角に交わる側面部とを有し、三角形形状または台形形状を貫欠した複数の台形状を入射端面部側に突設した導光板と、
光源と導光板とを保持するケースとを具備し、
光源は台形状の中心位置に対向して配置するので、光源からの光束コーンの中心部を最大限に利用し、上下左右方向に対する有効な光束コーンによって導光板の表面部と裏面部との上下方向に対して十分な全反射を引き起こし、表面部と裏面部とから臨界角を破る光線を得ることができる。
【００４１】
また、請求項１４に係る平面照明装置は、半導体発光素子からなる光源と、
光源からの光を導く入射端面部と、この入射端面部の反対側に位置する反射端面部と、入射端面部から導いた光を出射する表面部と、表面部の反対側に位置する裏面部と、入射端面部側と表面部とに直角に交わる側面部とを有し、三角形形状または台形形状を貫欠した複数の台形状を入射端面部側に突設するとともに光源を台形状の中心端に設ける空間を有した導光板と、
光源と導光板とを保持するケースとを具備し、
光源は台形状の中心位置に対向して配置することを特徴とする。
【００４２】
請求項１４に係る平面照明装置は、半導体発光素子からなる光源と、
光源からの光を導く入射端面部と、この入射端面部の反対側に位置する反射端面部と、入射端面部から導いた光を出射する表面部と、表面部の反対側に位置する裏面部と、入射端面部側と表面部とに直角に交わる側面部とを有し、三角形形状または台形形状を貫欠した複数の台形状を入射端面部側に突設するとともに光源を台形状の中心端に設ける空間を有した導光板と、
光源と導光板とを保持するケースとを具備し、
光源は台形状の中心位置に対向して配置するので、光源からの光線を無駄無く利用するとともに光源からの光束コーンの中心部を最大限に利用し、上下左右方向に対する有効な光束コーンによって導光板の表面部と裏面部との上下方向に対して十分な全反射を引き起こし、表面部と裏面部とから臨界角を破る光線を得ることができる。
【００４３】
【発明の実施の形態】
以下、本発明の実施の形態を添付図面に基づき説明する。
なお、本発明は、反射端面部方向に表面部と成す角度と裏面部と成す角度とが等しい三角柱形状に入射端面部を欠切し、この欠切部分で光源からの光線を表面部方向と裏面部方向とに偏向し、光源側に突設する入射端面部の台形状の凸凹構造または凸構造の台形状内に対称性を有する三角形形状を貫欠することにより、三角形形状や台形形状で上記偏向された光線を全反射させて反射端面部方向に進ませながら表面部から出射させて明るく均一な出射光が得られる導光板および平面照明装置を提供することにある。
【００４４】
図１は本発明に係る平面照明装置の略構成図、図２〜図５は本発明に係る導光板の入射端面部の略形状図、図６、図７および図８は光線の軌跡図である。
【００４５】
図１の平面照明装置１は、複数の光源１３と、これら光源１３に対向接近した位置が台形状８に突設し、光源１３からの光を導く入射端面部３と、この入射端面部３の反対側に位置する反射端面部４と、入射端面部３から導いた光を出射する表面部５と、この表面部５の反対側に位置する裏面部６と、これら表面部５と反射端面部４とに直角に交わる側面部７を有する導光板２の他、図示しない反射体等で構成されている。
【００４６】
導光板２は、屈折率が１．４〜１．７程度からなるアクリル樹脂（ＰＭＭＡ）、ポリカーボネート（ＰＣ）、ポリスチレン、ポリプロピレン、ポリエステル、ポリオレフィンやスチレンとアクリロニトリルとの共重合体、スチレンとブタジエンとの共重合体、スチレンとメチルメタクルレートとの共重合体等の透明な樹脂からなる。
【００４７】
また、図示しないが、導光板２の表面部５または／および裏面部６には凸状、凹状やプリズムおよびＶ溝等いずれかの加工が施されている。これにより、点光源１３から導光板２内に導いた光をこれら加工部分で反射や屈折等を行い、表面部５に出射するようにしたり、裏面部６に施されたシボ加工（梨地加工）や白色系印刷等により裏面部６で散乱させて表面部５に出射させている。
【００４８】
ここで、導光板２は、光源１３に対向接近した位置のため、光源１３からの光束コーンの中心部を利用しており、光源１３から取り入れた光を屈折率ｎに応じた屈折角βで入射し、光源１３側の側面部７の法線と成る屈折角βが０≦｜β｜≦ｓｉｎ-1（１／ｎ）を満たす範囲で導光板２内を進行する。
【００４９】
また、導光板２の屈折率ｎがｎ＝１．４９の場合、屈折角βは約４２°となり、この範囲で導光板２内を進行するとともに導光板２と空気層の屈折率（ｎ＝１）との境界面で全反射を生じ、この臨界角も約φ＝４２°となる。
【００５０】
また、導光板２は、図２〜４に示すような入射端面部３を突設し隣接する台形状８の斜辺８ｂが互いに接しないフラット面８ｄが介在する台形状８の凸凹構造、図５に示すような入射端面部３を突設し隣接する台形状８の斜辺８ｂが互いに接するような谷部８ｅを介して台形状８が連続する凸構造で構成される。
【００５１】
さらに、導光板２は、入射端面部３に突設する台形状８内に図２に示すような対称性を有した三角形形状９を表面部５から裏面部６まで貫欠させたり、図３に示すような台形状８内の中心位置に入射端面部３方向が短く反射端面部４方向が長い台形形状１０を表面部５から裏面部６まで貫欠させたり、図４に示すような台形状８内の一部（光源１３と対面する部分）を欠切するように中心位置に反射端面部４方向を底辺とする台形形状１１を表面部５から裏面部６まで貫欠させたりしている。
【００５２】
また、導光板２は、図１に示すように、入射端面部３に突設する台形状８を反射端面部４方向に表面部５と成す角度と裏面部６と成す角度とが等しい三角柱形状１２に欠切している。これにより、光源１３からの光線を導光板２に入射させた際、光源１３からの光線を三角柱形状１２によって最初から表面部５方向と裏面部６方向に進ませ、光源１３からの入射光がより多く臨界角を破るように光線量を増やしている。
【００５３】
さらに、図示しないが、光源１３を導光板２の台形状８の中心端に設ければ、光源１３の左右方向（両側面部７）の光線も導光板２の台形状部８に放出できるので、表面部５と裏面部６とから臨界角を破る光線を得ることができる。この場合には、光源１３と導光板２を一体化にすることができる。
【００５４】
また、図２の例における三角形形状９は、１つの台形状８に対して２つから成り、それぞれ対称性を保って貫切される。さらに説明すると、図２（ａ）の例では、２つの三角形形状９の頂点９ｄが入射端面部３（光源１３）の方向に向き、２つの三角形形状９の隣接して互いに向き合う辺９ｃが平行に位置して１つの台形状８に対して２つの三角形形状９が貫切されている。図２（ｂ）の例では、２つの三角形形状９の頂点９ｄが入射端面部３（光源１３）の方向に向き、２つの三角形形状９の間隔が頂点９ｄ側の方が狭くなるように１つの台形状８に対して２つの三角形形状９が貫切されている。
【００５５】
尚、図示はしないが、三角形形状９は、２つの三角形形状９の頂点９ｄが反射端面部４の方向に向き、三角形形状９の間隔が頂点９ｄ側の方が狭くなるように１つの台形状８に対して２つ貫切してもよい。
【００５６】
そして、図２（ｂ）に示すように、入射端面部３に台形状８の凸凹構造を有するとともに突設した台形状８内に対称性を有する２つの三角形形状９の頂点９ｄが入射端面部３の方向に向き、２つの三角形形状９の間隔が頂点９ｄ側の方が狭くなるように１つの台形状８に対して２つの三角形形状９を貫切させた構成において、光源１３から入射した光線は、対称性を有した左右の三角形形状９における互いの斜辺９ｃで全反射を繰り返しながら反射端面部４方向に直進する少ない光線と、光源１３から入射し左右の三角形形状９の傾斜辺９ａで全反射をして両側面部７方向に進み、この傾斜辺９ａに対向する突設する台形形状８の斜辺８ｂで再び全反射をして反射端面部４方向に進む多くの光線と、光源１３から２つの三角形形状９の間から直射光線とともに互いに混ざりながら反射端面部４方向に進む。
【００５７】
尚、図２（ｂ）では、突設する台形状８の凸凹構造の先端面８ａと三角形形状９の底辺９ｂとが平行であるが、この底辺９ｂは先端面８ａと平行でなくても良い。
【００５８】
ここで、図２（ｂ）の構成に於ける光線の軌跡図を図６に示す。図６において、光源１３から入射した光線は、導光板２の上下左右方向に対して有効な光束コーンが存在する光束コーンの中心部が２つの三角形形状９の傾斜辺９ａと斜辺９ｃとの間に分布し、これら有効な光線が直接２つの三角形形状９の傾斜辺９ａで全反射をして両側面部７方向に進み、この傾斜辺９ａに対向する突設した台形状部８の斜辺８ｂで再び全反射をして反射端面部４方向に進む光線と、台形状部８の斜辺８ｂに進まず隣接する台形形状部８方向の台形状部８の存在しない導光板２の本体方向に進む光線とがある。
【００５９】
また、三角形形状９の斜辺９ｃの頂点９ｄ付近で全反射した光線は、互いに対向する斜辺９ｃ方向に進み、一部はそのまま進み、一部は再度斜辺９ｃの頂点９ｄと反対方向付近で全反射をする。
【００６０】
さらに、２つの斜辺９ｃに達せずに、これらの２つの斜辺９ｃの間からの導光板２の反射端面部４方向に直進して各方向に進んだ光線は有効な光束コーンであるため、導光板２内に進みながら表面部５と裏面部６との上下方向に対して十分な全反射を引き起こしながら反射端面部４方向に進み、この間導光板２の表面部５や裏面部６に施した加工部分（プリズム、溝、凸凹形状、白色系印刷等）により臨界角を破って導光板２の外部に出射する。
【００６１】
また、２つの三角形形状９の頂点９ｄが入射端面部３の方向に向き、２つの三角形形状９の間隔が頂点９ｄ側の方が狭くなるように１つの台形状８に対して２つの三角形形状９を貫切して設けた場合も同様な効果を得ることができる。すなわち、図７の光線の軌跡図に示すように、光源１３から入射した光線は、導光板２の上下左右方向に対して有効な光束コーンが存在する光束コーンの中心部が２つの三角形形状９の傾斜辺９ａとの間に分布し、これら有効な光線が直接２つの三角形形状９の傾斜辺９ａで全反射をして両側面部７方向に進み、この傾斜辺９ａに対向する突設した台形状部８の斜辺８ｂで再び全反射をして反射端面部４方向に進む光線と、台形状部８の斜辺８ｂに進まず隣接する台形状部８方向の台形状部８の存在しない導光板２の本体方向に進む光線とがある。
【００６２】
さらに、２つの斜辺９ｃに達せずに、これら２つの斜辺９ｃの間からの導光板２の反射端面部４方向に直進して各方向に進んだ光線は有効な光束コーンであるため、導光板２内に進みながら表面部５と裏面部６との上下方向に対して十分な全反射を引き起こしながら反射端面部４方向に進み、この間導光板２の表面部５や裏面部６に施した加工部分（プリズム、溝、凸凹形状、白色系印刷等）により臨界角を破って導光板２の外部に出射する。
【００６３】
また、図２（ａ）に示す構成、すなわち、対称性を保って２つの三角形形状９の各頂点９ｄが入射端面部３方向に向き、２つの三角形形状９の隣接して互いに向き合う辺９ｃが平行に位置して１つの台形状８に対して２つの三角形形状９を貫切して設けた場合も同様な効果を得ることができる。
【００６４】
さらに、図示はしないが、三角形形状９は、導光板２の両側面部７側に位置する三角形形状９の対称位置に有る三角形形状９（両側面部７側から２番目の三角形形状９）を他の三角形形状９よりも小さく貫切する構成としてもよい。この構成によれば、両側面部７側に位置する三角形形状９の斜辺９ｃから全反射された光線は、他の三角形形状９よりも小さく貫切された対向する三角形形状９（両側面部側７から２番目の三角形形状９）によって阻止されることなく、導光板２の内側方向に容易に進むことができる。
【００６５】
また、他の三角形形状９よりも小さく貫切された三角形形状９の斜辺９ｃからの全反射された光線は、対向する両側面部７側の三角形形状９の斜辺９ｃで再度全反射して導光板２の内側方向に進む。
【００６６】
このように、三角形形状９を導光板２の両側面部７側に位置する三角形形状９の対称位置に有る三角形形状９を他の三角形形状９よりも小さくすることによって、光源１３からの光線を無駄なく利用してより明るい出射光を得ることが可能となる。また、輝度分布を制御することが可能で、同様な効果を光源１３の位置を台形状８の中心端から変位させることによっても可能である。
【００６７】
さらに、図３に示すように、入射端面部３に台形状８の凸凹構造を有するとともに突設した台形状８内の中心位置に入射端面部３方向が短い上辺１０ａと反射端面部４方向が長い底辺１０ｃと２つの等しい斜辺１０ｂからなる台形形状１０を貫欠させた構成とすることができる。この構成によれば、光源１３から入射した光線は、対称性を有した左右の斜辺１０ｂで全反射をして両側面部７方向に進み、この斜辺１０ｂに対向する突設した台形状部８の斜辺８ｂで再び全反射をして反射端面部４方向に進む多くの光線と、一度台形状８内の入射端面部３方向に近い台形形状１０の短い上辺１０ａ部を透過し再び台形形状１０の反射端面部４方向が長い底辺１０ｃ部を透過して反射端面部４方向に進む光線とが互いに混ざりながら反射端面部４方向に進む。
【００６８】
尚、この場合には、光源１３から空気層を通り、空気層から導光板２へ、再び導光板２から空気層、再度空気層から導光板２と進むので、結果としては１度の空気層から導光板２への屈折しか変わらない。
【００６９】
また、これらの光線は有効な光束コーンであるため、導光板２内に進みながら表面部５と裏面部６との上下方向に対して十分な全反射を引き起こしながら反射端面部４方向に進み、この間導光板２の表面部５や裏面部６に施した加工部分（プリズム、溝、凸凹形状、白色系印刷等）により臨界角を破って導光板２の外部に出射する。
【００７０】
さらに、図４に示すように、入射端面部３に台形状８の凸凹構造を有するとともに突設した台形状８内の一部を欠切するように台形状８の中心位置に反射端面部４方向を底辺１１ａとする三角形状１１を貫欠させた構成とすることができる。この構成によれば、光源１３から入射した光線は、対称性を有した左右の斜辺１１ｂで全反射をして両側面部７方向に進み、この斜辺１１ｂに対向する突設した台形状部８の斜辺８ｂで再び全反射をして反射端面部４方向に進む多くの光線と、直接三角形状１１の底辺１１ａ部に達し、透過して反射端面部４方向に進む光線とが互いに混ざりながら反射端面部４方向に進む。
【００７１】
また、突設した台形状８内の一部を欠切した所に光源１３からの斜辺１１ｂ方向寄りの斜めからの入射光線は、底辺１１ａ部で屈折して、やや垂線よりに戻されて互いに斜辺１１ｂ寄り方向に進みながら反射端面部４方向に進み、同様にこれらの光線は有効な光束コーンであるため、導光板２内に進みながら表面部５と裏面部６との上下方向に対して十分な全反射を引き起こしながら反射端面部４方向に進み、この間導光板２の表面部５や裏面部６に施した加工部分（プリズム、溝、凸凹形状、白色系印刷等）により臨界角を破って導光板２の外部に出射する。
【００７２】
さらに、図５に示すように、突設し隣接する台形状８の斜辺８ｂが互いに接するような谷部８ｅを介して台形状８を入射端面部３に設けた凸構造では、三角形形状９や台形形状１０等の傾斜辺９ａや斜辺１０ｂおよび斜辺１１ｂ等で全反射した光線を再び台形状部８の斜辺８ｂで全反射させて反射端面部４方向に進む光線と、台形状部８の斜辺８ｂに進まず隣接する台形状部８方向に進む光線を互いに重ね合わせて台形状部８の中心位置から入射する光線との輝度が同程度になるようにする。この場合の導光板２は小型形状に適している。
【００７３】
このように、本例の導光板および平面照明装置は、入射端面部３に台形状８の凸凹構造や凸構造を有し、突設した台形状８内に対称性な２つの三角形形状９や台形形状１０および突設した台形状８内の一部を欠切するように台形形状１１等を貫欠させて、これらによる全反射した光線を再び台形状８の斜辺８ｂでの全反射によって導光板２全体を明るくする構成であるが、導光板２の長さや幅等のサイズ、光源１３のピッチ（数量）、必要出射光の輝度等の目的に合わせるために、三角形形状９の傾斜辺９ａや台形形状１０の斜辺１０ｂおよび台形形状１１の斜辺１１ｂと台形状８の斜辺８ｂとの位置関係により、光線の方向およびその方向の光量をコントロールすることができる。例えば台形状８の形状（斜辺８ｂ）を固定にし、これに対向する傾斜辺９ａや斜辺１０ｂおよび斜辺１１ｂの位置変化させることで光線の方向およびその方向の光量をコントロールできる。
【００７４】
さらに説明すると、図８に示すように、光源１３（ＬＥＤ）のポイント（Ｌ，０）からの光線Ｌｉが入射角θｉで入射した時の座標は（Ｌ＊ｔａｎ（θｉ），０）となり、出射角θｔの屈折で導光板２内に光線Ｌａが進み、傾斜辺９ａの端の座標（ｘ２，ｙ２）に到達するような傾斜辺９ａの両端の座標（ｘ１，ｙ１）と（ｘ２，ｙ２）に対応する光源１３の発散角は下記表１に示される。表１は本発明に係る光源と光線の軌跡との関係表である。
【００７５】
【表１】

Figure 0004260358
【００７６】
このように、光源１３からの光線分布に対応して傾斜辺９ａの両端の座標（ｘ１，ｙ１）と（ｘ２，ｙ２）を定めることによって、台形状８の斜辺８ｂに対して傾斜辺９ａで全反射させる光線を決定することができる。
【００７７】
光源１３は、青、緑、赤等の単色や白色のＬＥＤおよびレーザ等からなる。光源１３の形状としては、平面やレンズ付きのものであっても良く、入射端面部３の突設する台形状８の凸凹構造や凸構造の先端面８ａに平行であるとともに中心に対向させて載置する。
【００７８】
また、光源１３は、半導体発光素子であるので、光の放射方向が直進はもちろんであるが、左右上下にもおよぶ。そこで、図示はしないが、光源１３を台形状８の中心の端に（台形状８の内側）設ければ、両側面部７方向に進んだ光線が突設する台形形状部８で全反射ができ、反射端面部４方向に進むことができる。
【００７９】
図示しない反射体は、熱可塑性樹脂に例えば酸化チタンのような白色材料を混入したシートや熱可塑性樹脂のシートにアルミニウム等の金属蒸着を施したり金属箔を積層した物や、シート状金属およびこれらのフィルム形状にしたものからなる。この反射体は、光源１３からの光が導光板２によって表面部５に出射させる光以外の光を反射または乱反射し、再度導光板２に入射させて光源１３からの光を全て表面部５から出射するようにする。
【００８０】
このように、本発明の導光板および平面照明装置は、導光板の点光源に対応した位置に台形状を突設し、この台形状内に対称性を有した三角形形状や台形形状に貫欠し、光源からの光線を突設した台形状の側面側や貫欠した三角形形状や台形状の辺で全反射をし、光線を左右に広げるとともに突設した台形状の光源側を楔状のように三角柱形状に欠切して導光板に入射する時点で光源からの光線を表面部方向や裏面部方向に導くことにより、導光板の大きさに係り無く斑の無い均一で明るい出射光を得ることが出来る。
【００８１】
【発明の効果】
以上のように、請求項１に係る導光板は、入射端面部側に台形状の凸凹構造を有し、光源側に突設する台形状の平行な対辺の短辺を入射端面部とするとともに光源側に突設する台形状内に入射端面部方向が短く、反射端面部方向が長い台形形状を貫欠するので、対称性を有した三角形形状で全反射した光線が反射端面部方向に直進するものと、両側面部方向に進み突設する台形状部で再び全反射をして反射端面部方向に進むものと、また光源からの直射光線とともに互いに混ざりながら反射端面部方向に進むとともに光源からの光束コーンの中心部を利用するので、上下左右方向に対し有効な光束コーンが存在し、導光板の表面部と裏面部との上下方向に対して十分な全反射を引き起こすことができ、表面部と裏面部とから臨界角を破る光線を得ることができる。
また、対称性を有した三角形形状で全反射した光線が反射端面部方向に直進するものと、両側面部方向に進み突設する台形状部で再び全反射をして反射端面部方向に進むものと、また光源からの直射光線とともに互いに混ざりながら反射端面部方向に進むとともに光源からの光束コーンの中心部を利用するので、上下左右方向に対し有効な光束コーンが存在し、導光板の表面部と裏面部との上下方向に対して十分な全反射を引き起こすことができるとともに光源の左右方向の光線も台形状部に放出できる。
【００８２】
また、請求項２に係る導光板は、入射端面部側に台形状の凸構造を有し、光源側に突設する台形状の平行な対辺の短辺を入射端面部とするとともに光源側に突設する台形状内に対称性を有した三角形形状を貫欠するので、対称性を有した三角形形状で全反射した光線が反射端面部方向に直進するものと、両側面部方向に進み突設する台形状部で再び全反射をして反射端面部方向に進むものと、また光源からの直射光線とともに互いに混ざりながら反射端面部方向に進むとともに光源からの光束コーンの中心部を利用するので、上下左右方向に対し有効な光束コーンが存在し、導光板の表面部と裏面部との上下方向に対して十分な全反射を引き起こすことができ、表面部と裏面部とから臨界角を破る光線を得ることができる。
また、対称性を有した三角形形状で全反射した光線が反射端面部方向に直進するものと、両側面部方向に進み突設する台形状部で再び全反射をして反射端面部方向に進むものと、また光源からの直射光線とともに互いに混ざりながら反射端面部方向に進むとともに光源からの光束コーンの中心部を利用するので、上下左右方向に対し有効な光束コーンが存在し、導光板の表面部と裏面部との上下方向に対して十分な全反射を引き起こすことができるとともに光源の左右方向の光線も台形状部に放出できる。
【００８５】
さらに、請求項３に係る導光板は、三角形形状を、対称な２つの三角形形状の３つの頂点の何れかの頂点が入射端面部の方向に向き、互いに向き合う辺が平行に位置してなるので、小さな突設の台形状部で対称性を有した三角形形状で全反射した光線が反射端面部方向に直進するものと、両側面部方向に進み突設する台形状部で再び全反射をして反射端面部方向に進むものと、また光源からの直射光線とともに互いに混ざりながら反射端面部方向に進むとともに光源からの光束コーンの中心部を利用するので、上下左右方向に対し有効な光束コーンが存在し、導光板の表面部と裏面部との上下方向に対して十分な全反射を引き起こすことができ、表面部と裏面部とから臨界角を破る光線を得ることができる。
【００８６】
また、請求項４に係る導光板は、三角形形状を、対称な２つの三角形形状の３つの頂点の何れかの頂点が入射端面部の方向に向き、三角形形状の間隔が頂点側の方が狭く位置してなるので、対称性を有した三角形形状で全反射した光線が反射端面部方向に直進する少ない光線と、両側面部方向に進み突設する台形状部で再び全反射をして反射端面部方向に進む多くの光線と、また光源からの直射光線とともに互いに混ざりながら反射端面部方向に進むとともに光源からの光束コーンの中心部を利用するので、上下左右方向に対し有効な光束コーンが存在し、導光板の表面部と裏面部との上下方向に対して十分な全反射を引き起こすことができ、表面部と裏面部とから臨界角を破る光線を得ることができる。
【００８７】
さらに、請求項５に係る導光板は、三角形形状を、対称な２つの三角形形状の３つの頂点の何れかの頂点が反射端面部の方向に向き、三角形形状の間隔が頂点側の方が狭く位置してなるので、対称性を有した三角形形状で全反射した光線が反射端面部方向に直進するものと、両側面部方向に進み突設する台形状部で再び全反射をして反射端面部方向に進むものと、また光源からの直射光線とともに互いに混ざりながら反射端面部方向に進むとともに光源からの光束コーンの中心部を利用するので、上下左右方向に対し有効な光束コーンが存在し、導光板の表面部と裏面部との上下方向に対して十分な全反射を引き起こすことができ、表面部と裏面部とから臨界角を破る光線を得ることができる。
【００８８】
また、請求項６に係る導光板は、突設する台形状と三角形形状とで、台形状の斜辺と、この斜辺に対向する三角形形状の辺とが常に光源からの光線を辺で全反射し、斜辺で再び全反射させて反射端面部方向へ導くので、三角形形状の配置角度に依存せずに台形状の斜辺で全反射を行うことができ、あらゆる大きさの導光板にも明るく斑の無い最適な設計ができる。
【００８９】
さらに、請求項７に係る導光板は、三角形形状のうち導光板の両側面部側に位置する三角形形状の対称位置に有る三角形形状が他の三角形形状よりも小さいので、この小さい三角形形状によって対称位置にある三角形形状からの全反射された光線の進行を阻止せずに、これらが配置されている反対側の側面部方向に光線を進行させることができるので、光線を無駄なく利用してより明るい出射光を得ることができる。
【００９０】
また、請求項８に係る導光板は、入射端面部側は台形状の凸凹構造を有し、光源側に突設する台形状の平行な対辺の短辺を入射端面部とするとともに光源側に突設する台形状内に入射端面部方向が短く、反射端面部方向が長い台形形状を貫欠するので、光源からの直進する光線を極めて少なくし、大部分の光線が両側面部方向に進み突設する台形状部で再び全反射をして反射端面部方向に進み、隣接する各台形状部での全反射光が互いに混ざりながら反射端面部方向に進むとともに光源からの光束コーンの中心部を利用するので、上下左右方向に対し有効な光束コーンが存在し、導光板の表面部と裏面部との上下方向に対して十分な全反射を引き起こすことができ、表面部と裏面部とから臨界角を破る光線を得ることができる。
【００９１】
さらに、請求項９に係る導光板は、中心位置に反射端面部方向を底辺とする台形形状に欠切した台形状を光源側に複数突設するので、光源から直進する光線を極めて少なくし、大部分の光線が両側面部方向に進み突設する台形状部で再び全反射をして反射端面部方向に進み、隣接する各台形状部での全反射光が互いに混ざりながら反射端面部方向に進むとともに光源からの光束コーンの中心部を利用するので、上下左右方向に対し有効な光束コーンが存在し、導光板の表面部と裏面部との上下方向に対して十分な全反射を引き起こすことができ、表面部と裏面部とから臨界角を破る光線を得ることができる。
【００９２】
また、請求項１０に係る導光板は、入射端面部に突設する台形状は、反射端面部方向に表面部と成す角度と裏面部と成す角度とが等しい台形形状に欠切するので、導光板に入射する入射光線が最初から表面部方向と裏面部方向に進み、より多くの臨界角を破る光線量を増やすことができ、均一で明るい輝度を得ることができる。
【００９３】
さらに、請求項１１に係る導光板は、表面部に導光板内の光を出射または／および裏面部方向に屈折または／および反射させるプリズム、溝および凸凹形状のいずれかを有するので、導光板内の臨界角に満たない光線を屈折させて表面部から出射させたり、全反射する光線の位置をコントロールして裏面部方向に偏向させることができ、表面部や裏面部からコントロールしながら光線を出射することができる。
【００９４】
また、請求項１２に係る導光板は、裏面部に導光板内の光を出射または／および表面部方向に屈折または／および反射させるプリズム、溝および凸凹形状ならびに白色系印刷のいずれかを有するので、導光板内の臨界角に満たない光線を屈折させて裏面部から出射させたり、全反射する光線の位置をコントロールして表面部方向に偏向させたり、裏面部に到達する光線を反射させることができ、表面部や裏面部からコントロールしながら光線を出射することができる。
【００９５】
さらに、請求項１３に係る平面照明装置は、半導体発光素子からなる光源と、光源からの光を導く入射端面部と、この入射端面部の反対側に位置する反射端面部と、入射端面部から導いた光を出射する表面部と、表面部の反対側に位置する裏面部と、入射端面部と表面部側とに直角に交わる側面部とを有し、三角形形状または台形形状を貫欠した複数の台形状を入射端面部側に突設した導光板と、光源と導光板とを保持するケースとを具備し、光源は台形状の中心位置に対向して配置するので、光源からの光束コーンの中心部を最大限に利用し、上下左右方向に対する有効な光束コーンによって導光板の表面部と裏面部との上下方向に対して十分な全反射を引き起こし、表面部と裏面部とから臨界角を破る光線が得られ、明るく均一な輝度を得ることができる。
【００９６】
また、請求項１４に係る平面照明装置は、半導体発光素子からなる光源と、光源からの光を導く入射端面部と、この入射端面部の反対側に位置する反射端面部と、入射端面部から導いた光を出射する表面部と、表面部の反対側に位置する裏面部と、入射端面部側と表面部とに直角に交わる側面部とを有し、三角形形状または台形形状を貫欠した複数の台形状を入射端面部側に突設するとともに光源を台形状の中心端に設ける空間を有した導光板と、光源と導光板とを保持するケースとを具備し、光源は台形状の中心位置に対向して配置するので、光源からの光線を無駄無く利用するとともに光源からの光束コーンの中心部を最大限に利用し、上下左右方向に対する有効な光束コーンによって導光板の表面部と裏面部との上下方向に対して十分な全反射を引き起こし、表面部と裏面部とから臨界角を破る光線が得られ、明るく均一な輝度を得ることができる。
【図面の簡単な説明】
【図１】本発明に係る平面照明装置の略構成図
【図２】本発明に係る導光板の入射端面部の略形状図
【図３】本発明に係る導光板の入射端面部の略形状図
【図４】本発明に係る導光板の入射端面部の略形状図
【図５】本発明に係る導光板の入射端面部の略形状図
【図６】本発明に係る光線の軌跡図
【図７】本発明に係る光線の軌跡図
【図８】本発明に係る光線の軌跡図
【図９】従来の導光板における光線の軌跡図
【符号の説明】
１…平面照明装置、２…導光板、３…入射端面部、４…反射端面部、５…表面部、６…裏面部、７…側面部、８…台形状、８ａ…先端面、８ｂ…斜辺、８ｄ…フラット面、８ｅ…谷部、９…三角形形状、９ａ…傾斜辺、９ｂ…底辺、９ｃ…斜辺、９ｄ…頂点、１０…台形形状、１０ａ…上辺、１０ｂ…斜辺、１０ｃ…底辺、１１…三角形状、１１ａ…底辺、１１ｂ…斜辺、１２…三角柱形状、１３…光源、α…臨界角、β…屈折角、ｎ…屈折率、θｉ…入射角、θｔ…出射角、Ｌａ，Ｌｉ…光線、Ｌｆ…屈折光線、Ｌｐ…プリズムを透過した屈折光線。[0001]
BACKGROUND OF THE INVENTION
In this invention, the light source is a point light source such as an LED, and the light from the point light source is dispersed in the left-right direction by utilizing total reflection or the like, thereby realizing uniform emission light that can be used for a backlight of a small liquid crystal display device or the like The present invention relates to a light guide plate and a flat illumination device.
[0002]
[Prior art]
As a conventional light guide plate and flat illumination device, the back surface side of the light guide plate is dot-printed with white ink or the like and a reflection sheet is provided, and a convex shape is formed on the surface of the light guide plate so as to correspond to a point light source such as an LED. It is known that linear or non-linear gradation processing is applied to the concave or concave shape, and the brightness is improved by reflecting or refracting the light from the light source at the convex or concave shaped portions by the action of light diffusion or condensing. It has been.
[0003]
In addition, as a conventional flat illumination device, for the purpose of emitting from the entire surface portion of the light guide plate, a point light source is arranged in parallel near the incident end surface portion of the light guide plate and the vertical direction (thickness direction) with respect to the entire surface of the incident end surface portion ) Is provided with a prism surface.
[0004]
Furthermore, as a conventional flat illumination device, for example, as shown in Japanese Patent Laid-Open No. 6-51130, a plurality of concave portions for installing point light sources are provided on the side surface on the incident surface side, and a substantially triangular shape is formed between the concave portions and the concave portions. A light cut in the direction of both sides of the point light source is taken into the light guide plate by the recess, and the light that has advanced in the direction of the both sides of the light guide plate is totally reflected by the substantially triangular cut portion and substantially anti-incident. There is also known one that advances in the surface direction to improve the luminance of the light guide plate.
[0005]
[Problems to be solved by the invention]
However, in the conventional light guide plate and the flat illumination device, dot printing is performed with white ink or the like on the back surface side of the light guide plate and a reflection sheet is provided, and the surface of the light guide plate is convex so as to correspond to a point light source such as an LED. In order to emit light from the light source to the surface using the action of light diffusion or condensing by reflection or refraction at the convex or concave shape part, applying linear or non-linear gradation processing to the shape or concave shape Light is controlled on the front and back sides of the light guide plate, but the side surface is simply reflected by the reflective sheet, and the side light is not used effectively. There are challenges.
[0006]
In addition, as a conventional flat illumination device, for the purpose of emitting from the entire surface portion of the light guide plate, a point light source is arranged in parallel near the incident end surface portion of the light guide plate and the vertical direction (thickness direction) with respect to the entire incident end surface portion In the configuration in which the prism surface is provided in FIG. 9, when the prism surface 51 is provided, as shown in FIG. 9, the prism surface 51 rather than the light beam Lf refracted by the flat incident surface 52 without the prism surface 51 (shown by a dotted line). The light beam Lp refracted in (shown by a solid line) travels to both ends and uses the light beam spread from each point light source. Since the incident angle is 35 ° and the energy intensity is 50%, the light emitted from both sides of the point light source has lower energy intensity than the straight light.
[0007]
In addition, light incident on the light guide plate depends on an incident angle that can be incident on the light guide plate, and is generally incident on the light guide plate at a refraction angle β corresponding to the refractive index n. The refraction angle β forming the line is 0 ≦ | β | ≦ sin-1The light guide plate travels within a range satisfying (1 / n).
[0008]
For this reason, the light in both side directions in the point light source is near the end of the light beam cone, and the incident angle range corresponding to the thickness direction of the light beam incident on the light guide plate is small. The range of directions becomes small, and the amount of light that causes total reflection is small. The critical angle can be expressed by sin α = (1 / n) at the boundary surface between the light guide plate and the air layer (refractive index n = 1). Since the refractive index of acrylic resin, which is a resin material used for general light guide plates, is about n = 1.49, the critical angle α is about α = 42 °, but causes total reflection. Since the amount of light at the exit angle close to the critical angle is small, there is little light that breaks the critical angle and exits the light guide plate. As a result, there is a problem that the luminance of the entire light guide plate is lowered.
[0009]
Furthermore, as a conventional flat illumination device, for example, as shown in Japanese Patent Laid-Open No. 6-51130, a plurality of concave portions for installing point light sources are provided on the side surface on the incident surface side, and a substantially triangular shape is formed between the concave portions and the concave portions. A light cut in the direction of both sides of the point light source is taken into the light guide plate by the recess, and the light that has advanced in the direction of the both sides of the light guide plate is totally reflected by the substantially triangular cut portion and substantially anti-incident. In the configuration in which the brightness of the light guide plate is improved by proceeding in the plane direction, total reflection is caused by a substantially triangular cut portion with respect to the light beam traveling in the left-right direction of the light source, but both in the point light source as described above. Since the light in the side direction is near the end of the light beam cone, the incident angle range corresponding to the thickness direction of the light beam incident on the light guide plate is small. For this reason, the vertical range incident on the light guide plate is reduced, and the amount of light at the exit angle close to the critical angle that causes total reflection is small. The amount of light that travels directly from the light source toward the reflection end face is large. As a result, there is a problem that luminance unevenness and luminance uniformity cannot be improved as the entire light guide plate.
[0010]
Therefore, the present invention has been made to solve such a problem, and its purpose is to project a trapezoidal shape at a position corresponding to the point light source, and to form a triangular shape or a trapezoidal shape having symmetry within this trapezoidal shape. The trapezoidal side of the light source protruding from the light source and the side of the trapezoidal triangular shape or trapezoidal side are totally reflected, spreading the light beam left and right and the protruding light source side of the trapezoidal light source By cutting the triangular prism shape like a wedge and entering the light guide plate, the light from the light source is guided toward the front and back surfaces, thereby reducing the loss due to the use of total reflection and reducing the size of the light guide plate. It is an object of the present invention to provide a light guide plate and a flat illumination device capable of obtaining bright outgoing light without any spots.
[0011]
[Means for Solving the Problems]
  In order to solve the above problem, the light guide plate according to claim 1 is an incident end surface portion.~ sideHas a trapezoidal uneven structureThe shorter side of the trapezoidal parallel opposite side protruding from the light source side is defined as the incident end face part.In addition, a trapezoidal shape projecting on the light source side has a trapezoidal shape with a short incident end face portion direction and a long reflecting end face portion direction.
[0012]
  The light guide plate according to claim 1 is an incident end surface portion.~ sideHas a trapezoidal uneven structureThe shorter side of the trapezoidal parallel opposite side protruding from the light source side is defined as the incident end face part.In addition, the trapezoidal shape projecting on the light source side has a trapezoidal shape with a short incident end face direction and a long reflection end face direction, so that the totally reflected light rays in the symmetrical triangle shape are reflected in the reflection end face direction. A straight head, a head-shaped portion that projects in the direction of both side surfaces, and is totally reflected again and travels in the direction of the reflective end surface, and also travels in the direction of the reflective end surface while being mixed with the direct light from the light source. Since the central part of the light beam cone from the light source is used, there is an effective light beam cone in the vertical and horizontal directions, and sufficient total reflection can be caused in the vertical direction of the front and back surfaces of the light guide plate. .
  In addition, a symmetrical triangular shape of the totally reflected light beam travels straight in the direction of the reflection end face, and a light beam that travels in the direction of both side faces and undergoes total reflection again and travels in the direction of the reflection end face. And the light beam cone from the light source is used in the direction of the reflection end face while being mixed with the direct light from the light source, and the center part of the light beam cone from the light source is used. In addition, it is possible to cause sufficient total reflection with respect to the vertical direction of the light source and the back surface portion, and also to emit light in the horizontal direction of the light source to the trapezoidal portion.
[0013]
  The light guide plate according to claim 2 is an incident end face portion.~ sideHas a trapezoidal convex structureThe shorter side of the trapezoidal parallel opposite side protruding from the light source side is defined as the incident end face part.In addition, a triangular shape having symmetry is cut out in a trapezoidal shape protruding on the light source side.
[0014]
  The light guide plate according to claim 2 is an incident end face portion.~ sideHas a trapezoidal convex structureThe shorter side of the trapezoidal parallel opposite side protruding from the light source side is defined as the incident end face part.In addition, a symmetrical triangular shape is cut through in a trapezoidal shape projecting on the light source side, so that the light beam totally reflected by the symmetrical triangular shape goes straight in the direction of the reflection end face, and both side surface portions The central part of the light beam cone from the light source while proceeding in the direction of the reflection end surface while mixing with each other with the direct light from the light source and proceeding in the direction of the reflection end surface part. Therefore, there is an effective light beam cone in the vertical and horizontal directions, and sufficient total reflection can be caused in the vertical direction between the front surface portion and the back surface portion of the light guide plate.
  In addition, a symmetrical triangular shape of the totally reflected light beam travels straight in the direction of the reflection end face, and a light beam that travels in the direction of both side faces and undergoes total reflection again and travels in the direction of the reflection end face. And the light beam cone from the light source is used in the direction of the reflection end face while being mixed with the direct light from the light source, and the center part of the light beam cone from the light source is used. In addition, it is possible to cause sufficient total reflection with respect to the vertical direction of the light source and the back surface portion, and also to emit light in the horizontal direction of the light source to the trapezoidal portion.
[0019]
  And claims3The light guide plate according to the triangular shape,Two symmetrical triangular shapesOne of the three verticesThe apex is directed in the direction of the incident end face, and the sides facing each other are located in parallel.
[0020]
  Claim3The light guide plate according to the triangular shape,Two symmetrical triangular shapesOne of the three verticesSince the apex is directed in the direction of the incident end face, and the sides facing each other are located in parallel, the light beam totally reflected in a triangular shape having symmetry with a small trapezoidal shape goes straight in the direction of the reflection end face. And the one with a trapezoidal shape that protrudes in the direction of both side surfaces, and is totally reflected again and proceeds in the direction of the reflective end surface, and also proceeds in the direction of the reflective end surface while being mixed with the direct light from the light source and from the light source. Since the center portion of the light beam cone is used, there is an effective light beam cone in the vertical and horizontal directions, and sufficient total reflection can be caused in the vertical direction between the front surface portion and the back surface portion of the light guide plate.
[0021]
  Claims4The light guide plate according to the triangular shape,Two symmetrical triangular shapesOne of the three verticesThe apex is directed in the direction of the incident end face, and the interval between the triangular shapes is narrower on the apex side.
[0022]
  Claim4The light guide plate according to the triangular shape,Two symmetrical triangular shapesOne of the three verticesSince the apex is directed toward the incident end face, and the interval between the triangle shapes is narrower on the apex side, the light rays totally reflected by the symmetrical triangle shape are less rays that go straight in the direction of the reflecting end face. In addition, many light rays that travel in the direction of both side surfaces and project again in the trapezoidal shape and go in the direction of the reflection end surface, and go directly to the reflection end surface while being mixed together with the direct light from the light source and from the light source Since the center portion of the light beam cone is used, there is an effective light beam cone in the vertical and horizontal directions, and sufficient total reflection can be caused in the vertical direction between the front surface portion and the back surface portion of the light guide plate.
[0023]
  And claims5The light guide plate according to the triangular shape,Two symmetrical triangular shapesOne of the three verticesThe vertex is directed in the direction of the reflection end face, and the interval between the triangular shapes is narrower on the vertex side.
[0024]
  Claim5The light guide plate according to the triangular shape,Two symmetrical triangular shapesOne of the three verticesSince the vertex is directed in the direction of the reflection end face, and the interval between the triangle shapes is located closer to the apex side, the light beam totally reflected by the symmetrical triangle shape goes straight in the direction of the reflection end face, The trapezoidal part that protrudes in the direction of both side surfaces is totally reflected again and proceeds in the direction of the reflection end surface, and also proceeds in the direction of the reflection end surface while being mixed with the direct light from the light source, and the cone of light from the light source. Since the center portion is used, there is an effective light beam cone in the vertical and horizontal directions, and sufficient total reflection can be caused in the vertical direction between the front surface portion and the back surface portion of the light guide plate.
[0025]
  Claims6The light guide plate according to the present invention has a trapezoidal shape and a triangular shape, and the oblique side of the trapezoid and the triangular side opposite to the oblique side always reflect the light rays from the light source at the side, and again at the oblique side. The light is reflected and guided toward the reflection end face.
[0026]
  Claim6The light guide plate according to the present invention has a trapezoidal shape and a triangular shape, and the hypotenuse of the trapezoid and the triangular side opposite to the hypotenuse always reflect the light from the light source at the side, and again at the hypotenuse. Since the light is reflected and guided in the direction of the reflection end face, total reflection can be performed with a trapezoidal hypotenuse without depending on the triangular arrangement angle.
[0027]
  And claims7The light guide plate according to the present invention is characterized in that a triangular shape at a symmetrical position of a triangular shape located on both sides of the light guide plate in a triangular shape is smaller than other triangular shapes.
[0028]
  Claim7In the light guide plate according to the present invention, the triangular shape at the symmetrical position of the triangular shape located on both sides of the light guide plate among the triangular shapes is smaller than the other triangular shapes. The light rays can travel in the direction of the side surface on the opposite side where they are disposed, without preventing the propagation of the totally reflected light rays.
[0029]
  Claims8The light guide plate according to~ sideHas a trapezoidal uneven structureThe shorter side of the trapezoidal parallel opposite side protruding from the light source side is defined as the incident end face part.In addition, a trapezoidal shape projecting on the light source side has a trapezoidal shape with a short incident end face portion direction and a long reflecting end face portion direction.
[0030]
  Claim8The light guide plate according to~ sideHas a trapezoidal uneven structureThe shorter side of the trapezoidal parallel opposite side protruding from the light source side is defined as the incident end face part.In addition, the trapezoidal shape projecting on the light source side has a trapezoidal shape with a short incident end face direction and a long reflection end face direction. The light is emitted from the light source while proceeding in the direction of the surface part, and is totally reflected again in the protruding trapezoidal part and proceeds in the direction of the reflective end face part, and the total reflected light in each adjacent trapezoidal part travels in the direction of the reflective end face part while being mixed with each other. Since the center portion of the cone is used, there is an effective light beam cone in the vertical and horizontal directions, and sufficient total reflection can be caused in the vertical direction between the front surface portion and the back surface portion of the light guide plate.
[0031]
  And claims9The light guide plate according to the present invention has a reflection end face direction at the center as a base.TrapezoidA plurality of trapezoidal shapes notched in the shape are provided on the light source side.
[0032]
  Claim9The light guide plate according to the present invention has a reflection end face direction at the center as a base.TrapezoidMultiple trapezoidal shapes cut out in the shape of the light source are projected on the light source side, so that the amount of light that goes straight from the light source is extremely small, and most of the light rays go in the direction of both side surfaces and totally reflect again at the trapezoidal shape. Effective in the up / down / left / right directions because the light travels in the direction of the reflection end face and travels in the direction of the reflection end face while the total reflected light from the adjacent trapezoidal parts are mixed with each other and uses the center of the light beam cone from the light source. There is a cone, and sufficient total reflection can be caused in the vertical direction between the front surface portion and the back surface portion of the light guide plate.
[0033]
  Claims10In the light guide plate according to the present invention, the trapezoidal shape protruding from the incident end surface portion has the same angle formed with the front surface portion and the angle formed with the back surface portion in the reflection end surface portion directionTrapezoidIt is characterized by being cut out in the shape.
[0034]
  Claim10In the light guide plate according to the present invention, the trapezoidal shape protruding from the incident end surface portion has the same angle formed with the front surface portion and the angle formed with the back surface portion in the reflection end surface portion directionTrapezoidSince the shape is cut out, the incident light incident on the light guide plate proceeds from the beginning toward the front surface and the back surface, and the amount of light that breaks more critical angles can be increased.
[0035]
  And claims11The light guide plate according to the present invention is characterized in that it has any one of a prism, a groove, and an uneven shape that emits light and / or refracts and / or reflects light in the light guide plate in the direction of the back surface on the front surface.
[0036]
  Claim11The light guide plate according to the present invention has any one of a prism, a groove, and a concavo-convex shape that emits or / or refracts and / or reflects the light in the light guide plate on the front surface portion, so that the critical angle in the light guide plate is satisfied. The light beam can be refracted and emitted from the front surface portion, or can be deflected toward the back surface portion by controlling the position of the totally reflected light beam.
[0037]
  Claims12The light guide plate according to the present invention is characterized in that it has any one of prisms, grooves and irregularities, and white printing that emit light in the light guide plate and / or refract or reflect it in the front surface direction on the back surface.
[0038]
  Claim12The light guide plate according to the present invention has any of prisms, grooves and uneven shapes and white printing on the back surface to emit or / or refract or / reflect light in the light guide plate in the direction of the front surface. Light that does not reach the critical angle can be refracted and emitted from the back surface portion, the position of the totally reflected light beam can be deflected in the direction of the front surface portion, or the light beam reaching the back surface portion can be reflected.
[0039]
  And claims13A flat illumination device according to the present invention includes a light source composed of a semiconductor light emitting element,
  An incident end face that guides light from the light source, a reflective end face located on the opposite side of the incident end face, a surface that emits light guided from the incident end face, and a back face located on the opposite side of the surface And the incident end face and surface part~ sideAnd a plurality of trapezoidal shapes with a triangular shape or a trapezoidal shape penetrating the incident end surface portion.~ sideA light guide plate projecting from
  A case for holding a light source and a light guide plate;
  The light source is arranged to face the trapezoidal center position.
[0040]
  Claim13A flat illumination device according to the present invention includes a light source composed of a semiconductor light emitting element,
  An incident end face that guides light from the light source, a reflective end face located on the opposite side of the incident end face, a surface that emits light guided from the incident end face, and a back face located on the opposite side of the surface And the incident end face and surface part~ sideAnd a plurality of trapezoidal shapes with a triangular shape or a trapezoidal shape penetrating the incident end surface portion.~ sideA light guide plate projecting from
  A case for holding a light source and a light guide plate;
  Since the light source is placed facing the center position of the trapezoidal shape, the center part of the light beam cone from the light source is used to the maximum, and the upper and lower sides of the light guide plate on the top and bottom sides of the light guide plate by the effective light beam cone in the vertical and horizontal directions It is possible to obtain a light beam that causes sufficient total reflection with respect to the direction and breaks the critical angle from the front surface portion and the back surface portion.
[0041]
  Claims14A flat illumination device according to the present invention includes a light source composed of a semiconductor light emitting element,
  An incident end face that guides light from the light source, a reflective end face located on the opposite side of the incident end face, a surface that emits light guided from the incident end face, and a back face located on the opposite side of the surface And the incident end face~ sideAnd a plurality of trapezoidal shapes that have a triangular shape or a trapezoidal shape, and an incident end surface portion.~ sideAnd a light guide plate having a space for providing a light source at the center end of the trapezoidal shape,
  A case for holding a light source and a light guide plate;
  The light source is arranged to face the trapezoidal center position.
[0042]
  Claim14A flat illumination device according to the present invention includes a light source composed of a semiconductor light emitting element,
  An incident end face that guides light from the light source, a reflective end face located on the opposite side of the incident end face, a surface that emits light guided from the incident end face, and a back face located on the opposite side of the surface And the incident end face~ sideAnd a plurality of trapezoidal shapes that have a triangular shape or a trapezoidal shape, and an incident end surface portion.~ sideAnd a light guide plate having a space for providing a light source at the center end of the trapezoidal shape,
  A case for holding a light source and a light guide plate;
  Since the light source is placed opposite to the center of the trapezoidal shape, the light beam from the light source can be used without waste, and the central part of the light beam cone from the light source can be used to the maximum and guided by an effective light beam cone in the vertical and horizontal directions. Sufficient total reflection is caused with respect to the vertical direction of the front surface portion and the back surface portion of the optical plate, and a light beam that breaks the critical angle from the front surface portion and the back surface portion can be obtained.
[0043]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
In the present invention, the incident end face portion is cut out in a triangular prism shape in which the angle formed between the front surface portion and the back surface portion in the reflection end face portion direction is equal, and the light beam from the light source is changed to the surface portion direction at this cut-out portion. In the triangular shape or trapezoidal shape by penetrating in the direction of the back surface and penetrating the trapezoidal concave / convex structure of the incident end surface protruding from the light source side or the triangular shape having symmetry in the trapezoidal shape of the convex structure An object of the present invention is to provide a light guide plate and a flat illumination device which can emit bright and uniform emitted light by totally reflecting the deflected light beam and emitting it from the surface part while proceeding in the direction of the reflection end face part.
[0044]
FIG. 1 is a schematic diagram of a flat illumination device according to the present invention, FIGS. 2 to 5 are schematic diagrams of incident end surfaces of a light guide plate according to the present invention, and FIGS. 6, 7 and 8 are locus diagrams of light rays. is there.
[0045]
The flat illumination device 1 in FIG. 1 includes a plurality of light sources 13, incident end face portions 3 that project light in the trapezoidal shape 8 at positions facing and approaching these light sources 13, and the incident end face portions 3. The reflection end face part 4 located on the opposite side of the light source, the surface part 5 for emitting the light guided from the incident end face part 3, the back surface part 6 located on the opposite side of the surface part 5, the surface part 5 and the reflection end face In addition to the light guide plate 2 having the side surface portion 7 that intersects with the portion 4 at a right angle, the light guide plate 2 includes a reflector (not shown).
[0046]
The light guide plate 2 is made of acrylic resin (PMMA) having a refractive index of about 1.4 to 1.7, polycarbonate (PC), polystyrene, polypropylene, polyester, polyolefin, a copolymer of styrene and acrylonitrile, styrene and butadiene, And a transparent resin such as a copolymer of styrene and methyl methacrylate.
[0047]
Although not shown, the front surface portion 5 and / or the back surface portion 6 of the light guide plate 2 is processed with any one of a convex shape, a concave shape, a prism, a V-groove, and the like. As a result, the light guided from the point light source 13 into the light guide plate 2 is reflected or refracted by these processed portions and emitted to the front surface portion 5, or the texture processing applied to the back surface portion 6 (texture processing). Or scattered by the back surface portion 6 by white printing or the like and emitted to the front surface portion 5.
[0048]
Here, since the light guide plate 2 is located close to the light source 13, the light guide plate 2 uses the central portion of the light beam cone from the light source 13, and the light taken from the light source 13 has a refraction angle β corresponding to the refractive index n. The angle of refraction β that is incident and becomes the normal line of the side surface portion 7 on the light source 13 side is 0 ≦ | β | ≦ sin.-1The light guide plate 2 travels within a range satisfying (1 / n).
[0049]
When the refractive index n of the light guide plate 2 is n = 1.49, the refraction angle β is about 42 °, and the refractive index of the light guide plate 2 and the air layer (n = Total reflection occurs at the interface with 1), and this critical angle is also about φ = 42 °.
[0050]
Further, the light guide plate 2 has a trapezoidal convex / concave structure with a flat surface 8d that protrudes from the incident end face portion 3 as shown in FIGS. The incident end face portion 3 as shown in FIG. 6 is projected, and the trapezoidal shape 8 has a convex structure in which the trapezoidal shape 8 continues through a valley portion 8e where the oblique sides 8b of the adjacent trapezoidal shapes 8 contact each other.
[0051]
  Further, in the light guide plate 2, a triangular shape 9 having symmetry as shown in FIG. 2 is notched from the front surface portion 5 to the back surface portion 6 in a trapezoidal shape 8 protruding from the incident end surface portion 3. A trapezoidal shape 10 having a short incident end face 3 direction and a long reflecting end face 4 direction at the center position in the trapezoidal shape 8 as shown in FIG. The reflection end face 4 direction is the bottom side at the center so that a part of the shape 8 (the part facing the light source 13) is cut off.TrapezoidThe shape 11 is notched from the front surface portion 5 to the back surface portion 6.
[0052]
Further, as shown in FIG. 1, the light guide plate 2 has a triangular prism shape in which the angle formed between the trapezoidal shape 8 projecting on the incident end surface portion 3 and the front surface portion 5 in the direction of the reflection end surface portion 4 is equal to the angle formed between the back surface portion 6. 12 is cut off. As a result, when the light beam from the light source 13 is incident on the light guide plate 2, the light beam from the light source 13 is advanced from the beginning toward the front surface portion 5 and the rear surface portion 6 by the triangular prism shape 12, and the incident light from the light source 13 is reflected. The amount of light is increased to break the critical angle more.
[0053]
Furthermore, although not shown, if the light source 13 is provided at the center end of the trapezoidal shape 8 of the light guide plate 2, light beams in the left-right direction (both side surface portions 7) of the light source 13 can be emitted to the trapezoidal portion 8 of the light guide plate 2. A light beam that breaks the critical angle can be obtained from the front surface portion 5 and the back surface portion 6. In this case, the light source 13 and the light guide plate 2 can be integrated.
[0054]
In addition, the triangular shape 9 in the example of FIG. 2 is composed of two pieces with respect to one trapezoidal shape 8, and is cut through with keeping symmetry. More specifically, in the example of FIG. 2A, the apexes 9d of the two triangular shapes 9 are directed in the direction of the incident end face portion 3 (light source 13), and the adjacent sides 9c of the two triangular shapes 9 facing each other are parallel. Two triangular shapes 9 are cut through with respect to one trapezoidal shape 8. In the example of FIG. 2B, the apex 9d of the two triangular shapes 9 is directed in the direction of the incident end face 3 (light source 13), and the interval between the two triangular shapes 9 is 1 so that the apex 9d side is narrower. Two triangular shapes 9 are cut through one trapezoidal shape 8.
[0055]
Although not shown, the triangular shape 9 has one trapezoidal shape so that the vertexes 9d of the two triangular shapes 9 face the direction of the reflection end face 4, and the interval between the triangular shapes 9 is narrower on the vertex 9d side. Two may be cut through with respect to 8.
[0056]
Then, as shown in FIG. 2B, the vertex 9d of the two triangular shapes 9 having the concavo-convex structure of the trapezoidal shape 8 on the incident end surface portion 3 and having symmetry in the protruding trapezoidal shape 8 is the incident end surface portion. In the configuration in which the two triangular shapes 9 are cut through one trapezoidal shape 8 so that the distance between the two triangular shapes 9 is narrower on the apex 9d side. The light rays are a few light rays that go straight in the direction of the reflection end face 4 while repeating total reflection at the oblique sides 9c of the left and right triangular shapes 9 having symmetry, and the inclined sides 9a of the left and right triangular shapes 9 that are incident from the light source 13. The light source 13 is subjected to total reflection and proceeds in the direction of both side surface portions 7, many light rays that are again totally reflected by the oblique side 8 b of the trapezoidal shape 8 projecting from the inclined side 9 a and travel in the direction of the reflection end surface portion 4. From between two triangular shapes 9 While mixed together with Shako line proceeds to the reflection end surface four directions.
[0057]
In FIG. 2 (b), the protruding trapezoidal shape tip 8a of the convex-concave structure and the base 9b of the triangle 9 are parallel, but the base 9b may not be parallel to the tip 8a. .
[0058]
Here, a locus diagram of light rays in the configuration of FIG. 2B is shown in FIG. In FIG. 6, the light beam incident from the light source 13 is located between the inclined side 9a and the inclined side 9c of the two triangular shapes 9 at the center of the light beam cone where the effective light beam cones exist in the vertical and horizontal directions of the light guide plate 2. These effective rays are directly reflected by the two inclined sides 9a of the triangular shape 9 and proceed in the direction of the side surface portions 7, and at the hypotenuse 8b of the trapezoidal portion 8 projecting from the inclined sides 9a. A light beam that is totally reflected again and travels in the direction of the reflection end surface portion 4, and a light beam that travels toward the main body of the light guide plate 2 that does not proceed to the oblique side 8 b of the trapezoidal portion 8 and does not have the trapezoidal portion 8 in the adjacent trapezoidal shape 8 direction. There is.
[0059]
Further, the light beam totally reflected in the vicinity of the apex 9d of the hypotenuse 9c of the triangular shape 9 proceeds in the direction of the hypotenuse 9c facing each other, a part thereof proceeds as it is, and a part of the light is totally reflected again in the direction opposite to the apex 9d of the hypotenuse 9c. do.
[0060]
Furthermore, since the light beam that does not reach the two hypotenuses 9c but travels straight in the direction of the reflection end surface 4 of the light guide plate 2 from the two hypotenuses 9c and proceeds in each direction is an effective beam cone, While proceeding into the optical plate 2, it proceeds in the direction of the reflection end surface portion 4 while causing sufficient total reflection in the vertical direction of the front surface portion 5 and the back surface portion 6. During this time, the surface portion 5 and the back surface portion 6 of the light guide plate 2 are applied. The critical angle is broken by the processed part (prism, groove, uneven shape, white printing, etc.) and the light is emitted to the outside of the light guide plate 2.
[0061]
In addition, two triangular shapes are formed with respect to one trapezoidal shape 8 so that the vertexes 9d of the two triangular shapes 9 are directed in the direction of the incident end face 3 and the interval between the two triangular shapes 9 is narrower on the vertex 9d side. The same effect can be obtained also when it is provided through 9. That is, as shown in the locus diagram of the light beam in FIG. 7, the light beam incident from the light source 13 has two triangular cones 9 at the center of the light beam cone where the effective light beam cones exist in the vertical and horizontal directions of the light guide plate 2. The effective light beams are directly reflected by the two inclined sides 9a of the triangular shape 9 and proceed in the direction of the both side surface portions 7, and project from the inclined sides 9a. A light guide plate that undergoes total reflection again at the oblique side 8b of the shape portion 8 and proceeds in the direction of the reflection end face portion 4 and does not proceed to the oblique side 8b of the trapezoid shape portion 8 and has no trapezoidal portion 8 in the direction of the adjacent trapezoid portion 8 There are two rays traveling in the body direction.
[0062]
Further, since the light beam that does not reach the two hypotenuses 9c but travels straight in the direction of the reflection end face 4 of the light guide plate 2 from the two hypotenuses 9c and proceeds in each direction is an effective light beam cone, the light guide plate 2 and proceeding in the direction of the reflection end face part 4 while causing sufficient total reflection in the vertical direction of the front face part 5 and the back face part 6 while proceeding into the process 2, and during this time, processing applied to the front face part 5 and the back face part 6 of the light guide plate 2 The critical angle is broken by a portion (prism, groove, uneven shape, white printing, etc.) and the light is emitted to the outside of the light guide plate 2.
[0063]
Also, the configuration shown in FIG. 2A, that is, the vertices 9d of the two triangular shapes 9 are oriented in the direction of the incident end face portion 3 while maintaining symmetry, and the sides 9c of the two triangular shapes 9 adjacent to each other are facing each other. A similar effect can be obtained also when two triangular shapes 9 are provided through one trapezoidal shape 8 positioned in parallel.
[0064]
Further, although not shown, the triangular shape 9 is different from the triangular shape 9 (the second triangular shape 9 from the side surface portion 7 side) at the symmetrical position of the triangular shape 9 located on the side surface portion 7 side of the light guide plate 2. It is good also as a structure penetrated smaller than the triangular shape 9. FIG. According to this configuration, the light beam totally reflected from the hypotenuse 9c of the triangular shape 9 located on the side surface 7 side is opposed to the opposing triangular shape 9 (from the side surface side 7 that is cut through smaller than the other triangular shape 9). Without being blocked by the second triangular shape 9), it can easily proceed in the inner direction of the light guide plate 2.
[0065]
The light beam totally reflected from the oblique side 9c of the triangular shape 9 cut through smaller than the other triangular shape 9 is again totally reflected by the oblique side 9c of the triangular shape 9 on the opposite side surface portions 7 side, and light guide plate Proceed in the direction of 2.
[0066]
Thus, by making the triangular shape 9 in the symmetrical position of the triangular shape 9 located on the both side surface portions 7 side of the light guide plate 2 smaller than the other triangular shapes 9, the light rays from the light source 13 are wasted. It is possible to obtain brighter outgoing light by using without using. Further, the luminance distribution can be controlled, and the same effect can be obtained by displacing the position of the light source 13 from the center end of the trapezoid 8.
[0067]
Further, as shown in FIG. 3, the incident end surface 3 has a trapezoidal convex / concave structure, and the upper end 10a and the reflection end surface 4 direction are short at the center position in the protruding trapezoidal shape 8. A trapezoidal shape 10 composed of a long base 10c and two equal hypotenuses 10b can be formed as a notch. According to this configuration, the light beam incident from the light source 13 is totally reflected by the left and right oblique sides 10b having symmetry, proceeds in the direction of the both side surface portions 7, and the protruding trapezoidal portion 8 facing the oblique side 10b. A large number of light rays that are totally reflected again at the hypotenuse 8b and travel in the direction of the reflection end face portion 4 and once pass through the short upper side 10a of the trapezoid shape 10 close to the incident end face portion 3 direction in the trapezoid shape 8 are transmitted again. Light rays that pass through the base 10c having a long reflection end surface 4 direction and travel in the reflection end surface portion 4 direction travel in the reflection end surface portion 4 direction while being mixed with each other.
[0068]
In this case, the light source 13 passes through the air layer, proceeds from the air layer to the light guide plate 2, travels again from the light guide plate 2 to the air layer, and again from the air layer to the light guide plate 2. Only the refraction from the light to the light guide plate 2 is changed.
[0069]
In addition, since these light rays are effective light beam cones, the light rays proceed into the light guide plate 2 while causing sufficient total reflection with respect to the vertical direction of the front surface portion 5 and the back surface portion 6 and proceed in the direction of the reflection end surface portion 4. During this time, the critical angle is broken by the processed portions (prisms, grooves, irregularities, white printing, etc.) applied to the front surface portion 5 and the back surface portion 6 of the light guide plate 2 and emitted to the outside of the light guide plate 2.
[0070]
Further, as shown in FIG. 4, the reflecting end surface portion 4 is provided at the center position of the trapezoid 8 so that the incident end surface 3 has a concave-convex structure of the trapezoid 8 and a part of the protruding trapezoid 8 is cut off. It can be set as the structure which made the triangular shape 11 which makes a direction the base 11a penetrated. According to this configuration, the light ray incident from the light source 13 is totally reflected by the left and right oblique sides 11b having symmetry, proceeds in the direction of the both side surface portions 7, and the protruding trapezoidal portion 8 facing the oblique side 11b. Reflective end face while many light rays that are totally reflected again at the hypotenuse 8b and proceed in the direction of the reflection end face portion 4 and light rays that directly reach the base 11a portion of the triangle 11 and pass through and travel in the direction of the reflection end face portion 4 are mixed with each other Proceed in part 4 direction.
[0071]
In addition, incident light rays obliquely near the hypotenuse 11b direction from the light source 13 at portions where a part of the protruding trapezoidal shape 8 is cut off are refracted at the base 11a portion and are slightly returned from the perpendicular to each other. Since the light beam is an effective light beam cone while proceeding toward the hypotenuse 11b, the light beams are effective light beam cones. While proceeding in the direction of the reflection end face 4 while causing sufficient total reflection, the critical angle is broken by the processed parts (prisms, grooves, irregularities, white printing, etc.) applied to the front surface 5 and back surface 6 of the light guide plate 2 during this time. To the outside of the light guide plate 2.
[0072]
Furthermore, as shown in FIG. 5, in the convex structure in which the trapezoidal shape 8 is provided on the incident end surface portion 3 via the valley portion 8e that protrudes and is adjacent to the oblique sides 8b of the trapezoidal shape 8, the triangular shape 9 or The light beam totally reflected by the inclined side 9a, the oblique side 10b, the oblique side 11b, etc. of the trapezoidal shape 10 is totally reflected again by the oblique side 8b of the trapezoidal part 8 and proceeds in the direction of the reflection end face part 4, and the oblique side of the trapezoidal part 8 The light beams traveling in the direction of the adjacent trapezoidal portion 8 without proceeding to 8b are overlapped with each other so that the luminance of the light beam incident from the center position of the trapezoidal portion 8 becomes approximately the same. The light guide plate 2 in this case is suitable for a small shape.
[0073]
  As described above, the light guide plate and the flat illumination device of this example have the trapezoidal shape 8 and the convex and concave structure on the incident end surface portion 3, and two symmetrical triangular shapes 9 in the protruding trapezoidal shape 8. Cut out part of trapezoidal shape 10 and protruding trapezoidal shape 8TrapezoidThe configuration is such that the shape 11 or the like is made to penetrate, and the light totally reflected by these is again brightened by the total reflection at the hypotenuse 8b of the trapezoidal shape 8, but the size of the light guide plate 2 such as the length and width is increased. In order to meet the purpose such as the pitch (quantity) of the light source 13 and the luminance of the necessary emitted light, the inclined side 9a of the triangular shape 9 and the inclined side 10b of the trapezoidal shape 10TrapezoidDepending on the positional relationship between the hypotenuse 11b of the shape 11 and the hypotenuse 8b of the trapezoid 8, the direction of the light beam and the amount of light in that direction can be controlled. For example, by fixing the shape of the trapezoid 8 (the oblique side 8b) and changing the positions of the inclined side 9a, the inclined side 10b, and the inclined side 11b facing the trapezoidal shape 8, the direction of the light beam and the amount of light in that direction can be controlled.
[0074]
More specifically, as shown in FIG. 8, the coordinates when the light beam Li from the point (L, 0) of the light source 13 (LED) is incident at the incident angle θi are (L * tan (θi), 0), The light rays La travel into the light guide plate 2 due to refraction at the exit angle θt, and the coordinates (x1, y1) and (x2, y2) of both ends of the inclined side 9a reach the coordinates (x2, y2) of the end of the inclined side 9a. The divergence angle of the light source 13 corresponding to () is shown in Table 1 below. Table 1 is a relationship table between the light source and the ray trajectory according to the present invention.
[0075]
[Table 1]
Figure 0004260358
[0076]
In this way, by defining the coordinates (x1, y1) and (x2, y2) at both ends of the inclined side 9a corresponding to the light distribution from the light source 13, the inclined side 9a with respect to the inclined side 8b of the trapezoid 8 is obtained. The rays that are totally reflected can be determined.
[0077]
The light source 13 is composed of a single color such as blue, green, red, or a white LED, a laser, or the like. The shape of the light source 13 may be a flat surface or a lens, and is parallel to the convex / concave structure of the trapezoidal shape 8 projecting from the incident end face portion 3 or the front end surface 8a of the convex structure and opposed to the center. Place.
[0078]
Further, since the light source 13 is a semiconductor light emitting element, the light emission direction goes straight, but also extends to the left, right, up and down. Therefore, although not shown in the figure, if the light source 13 is provided at the center end of the trapezoid 8 (inside the trapezoid 8), total reflection can be performed by the trapezoidal shape portion 8 in which light rays traveling in the direction of the side surface portions 7 project. It is possible to proceed in the direction of the reflection end face 4.
[0079]
A reflector (not shown) includes a sheet in which a white material such as titanium oxide is mixed in a thermoplastic resin, a sheet in which a thermoplastic resin sheet is subjected to metal deposition such as aluminum or a metal foil laminated, a sheet metal, and these It is made of a film shape. The reflector reflects or irregularly reflects light other than the light emitted from the light source 13 to the surface portion 5 by the light guide plate 2 and is incident on the light guide plate 2 again, so that all the light from the light source 13 is transmitted from the surface portion 5. Let it go out.
[0080]
As described above, the light guide plate and the flat illumination device of the present invention project a trapezoidal shape at a position corresponding to the point light source of the light guide plate, and have a triangular shape or a trapezoidal shape with symmetry in the trapezoidal shape. The trapezoidal side of the light source from the light source protrudes, and the triangular shape or trapezoidal side that penetrates is totally reflected, spreading the light to the left and right, and the protruding light source side of the trapezoid is like a wedge When the light is cut into a triangular prism shape and incident on the light guide plate, the light from the light source is guided toward the front surface or back surface to obtain uniform and bright outgoing light without spots regardless of the size of the light guide plate. I can do it.
[0081]
【The invention's effect】
  As described above, the light guide plate according to claim 1 has the incident end surface portion.~ sideHas a trapezoidal uneven structureThe shorter side of the trapezoidal parallel opposite side protruding from the light source side is defined as the incident end face part.In addition, the trapezoidal shape projecting on the light source side has a trapezoidal shape with a short incident end face direction and a long reflection end face direction, so that the totally reflected light rays in the symmetrical triangle shape are reflected in the reflection end face direction. A straight head, a head-shaped portion that projects in the direction of both side surfaces, and is totally reflected again and travels in the direction of the reflective end surface, and also travels in the direction of the reflective end surface while being mixed with the direct light from the light source. Since the center of the light beam cone from the light source is used, there is an effective light beam cone in the vertical and horizontal directions, and sufficient total reflection can be caused in the vertical direction between the front and back surfaces of the light guide plate. A light beam that breaks the critical angle can be obtained from the front surface portion and the back surface portion.
  In addition, a symmetrical triangular shape of the totally reflected light beam travels straight in the direction of the reflection end face, and a light beam that travels in the direction of both side faces and undergoes total reflection again and travels in the direction of the reflection end face. And the light beam cone from the light source is used in the direction of the reflection end face while being mixed with the direct light from the light source, and the center part of the light beam cone from the light source is used. In addition, it is possible to cause sufficient total reflection with respect to the vertical direction of the light source and the back surface portion, and also to emit light in the horizontal direction of the light source to the trapezoidal portion.
[0082]
  The light guide plate according to claim 2 is an incident end face portion.~ sideHas a trapezoidal convex structureThe shorter side of the trapezoidal parallel opposite side protruding from the light source side is defined as the incident end face part.In addition, a symmetrical triangular shape is cut through in a trapezoidal shape projecting on the light source side, so that the light beam totally reflected by the symmetrical triangular shape goes straight in the direction of the reflection end face, and both side surface portions The central part of the light beam cone from the light source while proceeding in the direction of the reflection end surface while mixing with each other with the direct light from the light source and proceeding in the direction of the reflection end surface part. Therefore, there is an effective light beam cone in the vertical and horizontal directions, and sufficient total reflection can be caused in the vertical direction between the front and back surfaces of the light guide plate. A light beam that breaks the critical angle can be obtained.
  In addition, a symmetrical triangular shape of the totally reflected light beam travels straight in the direction of the reflection end face, and a light beam that travels in the direction of both side faces and undergoes total reflection again and travels in the direction of the reflection end face. And the light beam cone from the light source is used in the direction of the reflection end face while being mixed with the direct light from the light source, and the center part of the light beam cone from the light source is used. In addition, it is possible to cause sufficient total reflection with respect to the vertical direction of the light source and the back surface portion, and also to emit light in the horizontal direction of the light source to the trapezoidal portion.
[0085]
  And claims3The light guide plate according to the triangular shape,Two symmetrical triangular shapesOne of the three verticesSince the apex is directed in the direction of the incident end face, and the sides facing each other are located in parallel, the light beam totally reflected in a triangular shape having symmetry with a small trapezoidal shape goes straight in the direction of the reflection end face. And the one with a trapezoidal shape that protrudes in the direction of both side surfaces, and is totally reflected again and proceeds in the direction of the reflective end surface, and also proceeds in the direction of the reflective end surface while being mixed with the direct light from the light source and from the light source. Since the center part of the light beam cone is used, there is an effective light beam cone in the vertical and horizontal directions, and sufficient total reflection can be caused in the vertical direction between the front and back surfaces of the light guide plate. And a light beam that breaks the critical angle from the back surface portion.
[0086]
  Claims4The light guide plate according to the triangular shape,Two symmetrical triangular shapesOne of the three verticesSince the apex is directed toward the incident end face and the interval between the triangles is narrower on the apex side, the light beam totally reflected by the symmetrical triangle is less likely to travel straight in the direction of the reflecting end face. In addition, many light rays that travel in the direction of both side surfaces and project again in the trapezoidal shape and go in the direction of the reflection end surface, and go directly to the reflection end surface while being mixed together with the direct light from the light source and from the light source Since the center part of the light beam cone is used, there is an effective light beam cone in the vertical and horizontal directions, and sufficient total reflection can be caused in the vertical direction between the front and back surfaces of the light guide plate. And a light beam that breaks the critical angle from the back surface portion.
[0087]
  And claims5The light guide plate according to the triangular shape,Two symmetrical triangular shapesOne of the three verticesSince the vertex is directed in the direction of the reflection end face, and the interval between the triangle shapes is located closer to the apex side, the light beam totally reflected by the symmetrical triangle shape goes straight in the direction of the reflection end face, The trapezoidal part that protrudes in the direction of both side surfaces is totally reflected again and proceeds in the direction of the reflection end surface, and also proceeds in the direction of the reflection end surface while being mixed with the direct light from the light source, and the cone of light from the light source. Since the center part is used, there is an effective light beam cone in the vertical and horizontal directions, and sufficient total reflection can be caused in the vertical direction between the front and back parts of the light guide plate. A light beam that breaks the critical angle can be obtained.
[0088]
  Claims6The light guide plate according to the present invention has a trapezoidal shape and a triangular shape, and the hypotenuse of the trapezoid and the triangular side opposite to the hypotenuse always reflect the light from the light source at the side, and again at the hypotenuse. Reflected and guided in the direction of the reflective end face, it is possible to perform total reflection on the trapezoidal hypotenuse without depending on the triangular arrangement angle, and an optimal design that is bright and free of spots on light guide plates of all sizes it can.
[0089]
  And claims7In the light guide plate according to the present invention, the triangular shape at the symmetrical position of the triangular shape located on both sides of the light guide plate among the triangular shapes is smaller than the other triangular shapes. The light beam can travel in the direction of the side surface on the opposite side where the light beam is totally reflected, so that the light beam can be used without waste to obtain a brighter outgoing light. Can do.
[0090]
  Claims8The light guide plate according to~ sideHas a trapezoidal uneven structureThe shorter side of the trapezoidal parallel opposite side protruding from the light source side is defined as the incident end face part.In addition, the trapezoidal shape projecting on the light source side has a trapezoidal shape with a short incident end face direction and a long reflection end face direction. The light is emitted from the light source while proceeding in the direction of the surface part, and is totally reflected again in the protruding trapezoidal part and proceeds in the direction of the reflective end face part, and the total reflected light in each adjacent trapezoidal part travels in the direction of the reflective end face part while being mixed with each other. Since the center portion of the cone is used, there is an effective light beam cone in the vertical and horizontal directions, and sufficient total reflection can be caused in the vertical direction between the front and back surfaces of the light guide plate. A light beam that breaks the critical angle from the back surface can be obtained.
[0091]
  And claims9The light guide plate according to the present invention has a reflection end face direction at the center as a base.TrapezoidMultiple trapezoidal shapes cut out in the shape of the light source are projected on the light source side, so that the amount of light that goes straight from the light source is extremely small, and most of the light rays go in the direction of both side surfaces and totally reflect again at the trapezoidal shape. Effective in the up / down / left / right directions because the light travels in the direction of the reflection end face and travels in the direction of the reflection end face while the total reflected light from the adjacent trapezoidal parts are mixed with each other and uses the center of the light beam cone from the light source. A cone is present, and sufficient total reflection can be caused in the vertical direction of the front and back surfaces of the light guide plate, and a light beam that breaks the critical angle can be obtained from the front and back surfaces.
[0092]
  Claims10In the light guide plate according to the present invention, the trapezoidal shape protruding from the incident end surface portion has the same angle formed with the front surface portion and the angle formed with the back surface portion in the reflection end surface portion directionTrapezoidSince the shape is cut out, the incident light incident on the light guide plate advances from the beginning in the direction of the front and back, and the amount of light that breaks more critical angles can be increased, resulting in uniform and bright brightness. it can.
[0093]
  And claims11The light guide plate according to the present invention has any one of a prism, a groove, and a concavo-convex shape that emits or / or refracts and / or reflects the light in the light guide plate on the front surface portion, so that the critical angle in the light guide plate is satisfied. The light beam can be refracted and emitted from the front surface portion, or the position of the totally reflected light beam can be controlled to be deflected toward the back surface portion, and the light beam can be emitted while being controlled from the front surface portion or the back surface portion.
[0094]
  Claims12The light guide plate according to the present invention has any of prisms, grooves and uneven shapes and white printing on the back surface to emit or / or refract or / reflect light in the light guide plate in the direction of the front surface. Refracts rays that are less than the critical angle and emits them from the backside, controls the position of the totally reflected rays, deflects them toward the surface, and reflects the rays that reach the backside. It is possible to emit light while controlling from the backside.
[0095]
  And claims13The flat illumination device according to the present invention emits light guided from a light source composed of a semiconductor light emitting element, an incident end face part that guides light from the light source, a reflective end face part that is opposite to the incident end face part, and an incident end face part. A front surface portion, a back surface portion located on the opposite side of the front surface portion, an incident end surface portion, and a front surface portion.~ sideAnd a plurality of trapezoidal shapes with a triangular shape or a trapezoidal shape penetrating the incident end surface portion.~ sideA light guide plate projecting from the light source and a case for holding the light source and the light guide plate are disposed opposite to the trapezoidal center position, so that the central portion of the light beam cone from the light source is utilized to the maximum. However, the effective light beam cone in the vertical and horizontal directions causes sufficient total reflection in the vertical direction of the front and back surfaces of the light guide plate, and light rays that break the critical angle are obtained from the front and back surfaces, making it brighter. Uniform brightness can be obtained.
[0096]
  Claims14The flat illumination device according to the present invention emits light guided from a light source composed of a semiconductor light emitting element, an incident end face part that guides light from the light source, a reflective end face part that is opposite to the incident end face part, and an incident end face part. A front surface portion, a back surface portion opposite to the front surface portion, and an incident end surface portion~ sideAnd a plurality of trapezoidal shapes that have a triangular shape or a trapezoidal shape, and an incident end surface portion.~ sideAnd a light guide plate having a space for providing a light source at the center end of the trapezoidal shape, and a case for holding the light source and the light guide plate, and the light source is disposed opposite the central position of the trapezoidal shape. The light beam from the light source is used without waste and the center of the light beam cone from the light source is utilized to the maximum, and the effective light beam cone with respect to the vertical and horizontal directions is used in the vertical direction of the front and back portions of the light guide plate. Sufficient total reflection is caused, and a light beam that breaks the critical angle from the front surface portion and the back surface portion can be obtained, and bright and uniform luminance can be obtained.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of a flat illumination device according to the present invention.
FIG. 2 is a schematic view of an incident end surface portion of a light guide plate according to the present invention.
FIG. 3 is a schematic view of an incident end face portion of a light guide plate according to the present invention.
FIG. 4 is a schematic view of an incident end face portion of a light guide plate according to the present invention.
FIG. 5 is a schematic view of an incident end surface portion of a light guide plate according to the present invention.
FIG. 6 is a ray trajectory diagram according to the present invention.
FIG. 7 is a locus diagram of light rays according to the present invention.
FIG. 8 is a locus diagram of light rays according to the present invention.
FIG. 9 is a locus diagram of light rays in a conventional light guide plate.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Plane illuminating device, 2 ... Light guide plate, 3 ... Incidence end surface part, 4 ... Reflection end surface part, 5 ... Front surface part, 6 ... Back surface part, 7 ... Side surface part, 8 ... Trapezoid shape, 8a ... Tip surface, 8b ... Oblique side, 8d ... Flat surface, 8e ... Valley, 9 ... Triangular shape, 9a ... Inclined side, 9b ... Bottom side, 9c ... Oblique side, 9d ... Vertex, 10 ... Trapezoidal shape, 10a ... Top side, 10b ... Oblique side, 10c ... Bottom side , 11 ... triangular shape, 11 a ... bottom, 11 b ... hypotenuse, 12 ... triangular prism shape, 13 ... light source, α ... critical angle, β ... refraction angle, n ... refractive index, θi ... incidence angle, θt ... emission angle, La, Li ... light, Lf ... refracted light, Lp ... refracted light transmitted through the prism.

Claims (14)

光源からの光を導く入射端面部と、この入射端面部の反対側に位置する反射端面部と、前記入射端面部から導いた光を出射する表面部と、当該表面部の反対側に位置する裏面部と、前記表面部と前記入射端面部側とに直角に交わる側面部を有する導光板において、
前記入射端面部側は台形状の凸凹構造を有し、前記光源側に突設する台形状の平行な対辺の短辺を前記入射端面部とするとともに前記光源側に突設する台形状内に対称性を有した三角形形状を貫欠することを特徴とする導光板。An incident end face that guides light from the light source, a reflective end face located on the opposite side of the incident end face, a surface that emits light guided from the incident end face, and an opposite side of the surface. In the light guide plate having a back surface and a side surface that intersects at right angles to the front surface portion and the incident end surface portion side ,
The incident end face side have a rough structure of a trapezoidal shape, a trapezoidal in shape projecting to the light source side with the short side of the trapezoidal parallel opposite sides that project from the light source side and the incidence end face A light guide plate characterized by penetrating a triangular shape having symmetry. 光源からの光を導く入射端面部と、この入射端面部の反対側に位置する反射端面部と、前記入射端面部から導いた光を出射する表面部と、当該表面部の反対側に位置する裏面部と、前記表面部と前記入射端面部側とに直角に交わる側面部を有する導光板において、
前記入射端面部側は台形状の凸構造を有し、前記光源側に突設する台形状の平行な対辺の短辺を前記入射端面部とするとともに前記光源側に突設する台形状内に対称性を有した三角形形状を貫欠することを特徴とする導光板。An incident end face that guides light from the light source, a reflective end face located on the opposite side of the incident end face, a surface that emits light guided from the incident end face, and an opposite side of the surface. In the light guide plate having a back surface and a side surface that intersects at right angles to the front surface portion and the incident end surface portion side ,
The incident end face side have a convex structure trapezoidal, trapezoidal in shape projecting to the light source side with the short side of the trapezoidal parallel opposite sides that project from the light source side and the incidence end face A light guide plate characterized by penetrating a triangular shape having symmetry. 前記三角形形状は、対称な２つの前記三角形形状の３つの頂点の何れかの頂点が前記入射端面部の方向に向き、互いに向き合う辺が平行に位置してなることを特徴とする請求項１又は２記載の導光板。The triangular shape is oriented in any of vertex direction of the incident end face of the three vertices of the symmetric two said triangular shape, claim 1 or edges facing each other and characterized by being positioned in parallel 2. The light guide plate according to 2 . 前記三角形形状は、対称な２つの前記三角形形状の３つの頂点の何れかの頂点が前記入射端面部の方向に向き、前記三角形形状の間隔が前記頂点側の方が狭く位置してなることを特徴とする請求項１又は２記載の導光板。The triangle shape is such that any one of the three symmetric vertices of the triangle shape is oriented in the direction of the incident end face, and the interval between the triangle shapes is located closer to the vertex side. according to claim 1 or 2, wherein the light guide plate, characterized. 前記三角形形状は、対称な２つの前記三角形形状の３つの頂点の何れかの頂点が前記反射端面部の方向に向き、前記三角形形状の間隔が前記頂点側の方が狭く位置してなることを特徴とする請求項１又は２記載の導光板。The triangular shape is such that any one of the three symmetric vertices of the triangular shape is oriented in the direction of the reflective end face, and the interval between the triangular shapes is positioned closer to the vertex side. according to claim 1 or 2, wherein the light guide plate, characterized. 前記突設する台形状と前記三角形形状とは、前記台形状の斜辺と、この斜辺に対向する前記三角形形状の辺とが常に前記光源からの光線を前記辺で全反射し、前記斜辺で再び全反射させて前記反射端面部方向へ導くことを特徴とする請求項１〜５のいずれかに記載の導光板。The protruding trapezoidal shape and the triangular shape are such that the trapezoidal hypotenuse and the triangular side opposite the hypotenuse always totally reflect the light rays from the light source at the hypotenuse, and again at the hypotenuse. the light guide plate according to any one of claims 1 to 5, characterized in that leading to the reflection end surface direction by total reflection. 前記三角形形状は、前記導光板の両側面部側に位置する前記三角形形状の対称位置に有る前記三角形形状が他の前記三角形形状よりも小さいことを特徴とする請求項１〜６のいずれかに記載の導光板。The said triangular shape has the said triangular shape in the symmetrical position of the said triangular shape located in the both-sides surface part side of the said light-guide plate, It is smaller than the said other triangular shape, The one in any one of Claims 1-6 characterized by the above-mentioned. Light guide plate. 光源からの光を導く入射端面部と、この入射端面部の反対側に位置する反射端面部と、前記入射端面部から導いた光を出射する表面部と、当該表面部の反対側に位置する裏面部と、前記表面部と前記入射端面部側とに直角に交わる側面部を有する導光板において、
前記入射端面部側は台形状の凸凹構造を有し、前記光源側に突設する台形状の平行な対辺の短辺を前記入射端面部とするとともに前記光源側に突設する台形状内に前記入射端面部方向が短く、前記反射端面部方向が長い台形形状を貫欠することを特徴とする導光板。An incident end face that guides light from the light source, a reflective end face located on the opposite side of the incident end face, a surface that emits light guided from the incident end face, and an opposite side of the surface. In the light guide plate having a back surface and a side surface that intersects at right angles to the front surface portion and the incident end surface portion side ,
The incident end face side have a rough structure of a trapezoidal shape, a trapezoidal in shape projecting to the light source side with the short side of the trapezoidal parallel opposite sides that project from the light source side and the incidence end face A light guide plate having a trapezoidal shape with a short incident end face direction and a long reflection end face direction. 光源からの光を導く入射端面部と、この入射端面部の反対側に位置する反射端面部と、前記入射端面部から導いた光を出射する表面部と、当該表面部の反対側に位置する裏面部と、前記表面部と前記入射端面部側とに直角に交わる側面部を有し、前記光源側に突設する台形状の平行な対辺の短辺を前記入射端面部とする導光板において、
中心位置に前記反射端面部方向を底辺とする台形形状に欠切した台形状を前記光源側に複数突設することを特徴とする導光板。An incident end face that guides light from the light source, a reflective end face located on the opposite side of the incident end face, a surface that emits light guided from the incident end face, and an opposite side of the surface. and the bottom, have a side portion intersecting at a right angle to said surface portion and the incident end surface side, the light guide plate to the incident end face of the short side of the trapezoidal parallel opposite sides that project from the light source side ,
A light guide plate, wherein a plurality of trapezoidal shapes cut out in a trapezoidal shape with the reflection end face direction as a base at the center position are provided on the light source side. 前記入射端面部に突設する前記台形状は、前記反射端面部方向に前記表面部と成す角度と前記裏面部と成す角度とが等しい台形形状に欠切することを特徴とする請求項１〜９のいずれかに記載の導光板。The trapezoidal shape protruding from the incident end surface portion is cut out into a trapezoidal shape in which an angle formed with the front surface portion and an angle formed with the back surface portion are equal in the direction of the reflection end surface portion. The light guide plate according to any one of 9 . 前記表面部は、前記導光板内の光を出射または／および前記裏面部方向に屈折または／および反射させるプリズム、溝および凸凹形状のいずれかを有することを特徴とする請求項１〜１０のいずれかに記載の導光板。The said surface part has either a prism, a groove | channel, and uneven shape which radiate | emit or / and reflect the light in the said light-guide plate in the said back surface part direction, The any one of Claims 1-10 characterized by the above-mentioned. A light guide plate according to any one of the above. 前記裏面部は、前記導光板内の光を出射または／および前記表面部方向に屈折または／および反射させるプリズム、溝および凸凹形状ならびに白色系印刷のいずれかを有することを特徴とする請求項１〜１０のいずれかに記載の導光板。2. The back surface portion has any one of a prism, a groove and an uneven shape, and white printing, which emit or / and refract or reflect light in the light guide plate in the direction of the surface portion. The light guide plate according to any one of 10 to 10 . 半導体発光素子からなる光源と、
当該光源からの光を導く入射端面部と、この入射端面部の反対側に位置する反射端面部と、前記入射端面部から導いた光を出射する表面部と、該表面部の反対側に位置する裏面部と、前記入射端面部と前記表面部側とに直角に交わる側面部とを有し、三角形形状または台形形状を貫欠した複数の台形状を前記入射端面部側に突設した導光板と、
前記光源と前記導光板とを保持するケースとを具備し、
前記光源は前記台形状の中心位置に対向して配置することを特徴とする平面照明装置。A light source comprising a semiconductor light emitting element;
An incident end face part that guides light from the light source, a reflection end face part located on the opposite side of the incident end face part, a surface part that emits light guided from the incident end face part, and a position opposite to the surface part and the bottom of, and a side portion intersecting at a right angle to the said surface portion side to the incident end face, projecting from a plurality of trapezoidal shape that Nukiketsu a triangular or trapezoidal shape on the incident end face side guide A light plate,
A case for holding the light source and the light guide plate;
The flat illumination device according to claim 1, wherein the light source is disposed to face the center position of the trapezoidal shape. 半導体発光素子からなる光源と、
当該光源からの光を導く入射端面部と、この入射端面部の反対側に位置する反射端面部と、前記入射端面部から導いた光を出射する表面部と、該表面部の反対側に位置する裏面部と、前記入射端面部側と前記表面部とに直角に交わる側面部とを有し、三角形形状または台形形状を貫欠した複数の台形状を前記入射端面部側に突設するとともに前記光源を前記台形状の中心端に設ける空間を有した導光板と、
前記光源と前記導光板とを保持するケースとを具備し、
前記光源は前記台形状の中心位置に対向して配置することを特徴とする平面照明装置。A light source comprising a semiconductor light emitting element;
An incident end face part that guides light from the light source, a reflection end face part located on the opposite side of the incident end face part, a surface part that emits light guided from the incident end face part, and a position opposite to the surface part and the bottom of, and a said entrance end face side to the surface and side portions intersecting at right angles to, a plurality of trapezoidal shape that Nukiketsu a triangular or trapezoidal shape while projecting the incident end face side A light guide plate having a space for providing the light source at the center end of the trapezoidal shape;
A case for holding the light source and the light guide plate;
The flat illumination device according to claim 1, wherein the light source is disposed to face the center position of the trapezoidal shape.
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